From Defoe: Journal of a plague year (the 1664 outbreak in London)

from the first week in June the infection spread in a dreadful manner, and the bills rose high; the articles of the fever, spotted-fever, and teeth began to swell; for all that could conceal their distempers did it, to prevent their neighbours shunning and refusing to converse with them, and also to prevent authority shutting up their houses; which, though it was not yet practised, yet was threatened, and people were extremely terrified at the thoughts of it.

So, people that were well enough to do so were concealing/ignoring their symptoms, and making things worse.

People would be found out, too, because there were officials appointed to make sure of it:

'That these examiners be sworn by the aldermen to inquire and learn from time to time what houses in every parish be visited, and what persons be sick, and of what diseases, as near as they can inform themselves; and upon doubt in that case, to command restraint of access until it appear what the disease shall prove. And if they find any person sick of the infection, to give order to the constable that the house be shut up; and if the constable shall be found remiss or negligent, to give present notice thereof to the alderman of the ward.

The people found out were "shut up" (i.e. physically, in their houses, under guard):

'That these examiners be sworn by the aldermen to inquire and learn from time to time what houses in every parish be visited, and what persons be sick, and of what diseases, as near as they can inform themselves; and upon doubt in that case, to command restraint of access until it appear what the disease shall prove. And if they find any person sick of the infection, to give order to the constable that the house be shut up; and if the constable shall be found remiss or negligent, to give present notice thereof to the alderman of the ward.

that none be removed out of the house where he falleth sick of the infection into any other house in the city (except it be to the pest-house or a tent, or unto some such house which the owner of the said visited house holdeth in his own hands and occupieth by his own servants)

That every house visited be marked with a red cross of a foot long in the middle of the door, evident to be seen, and with these usual printed words, that is to say, "Lord, have mercy upon us," to be set close over the same cross, there to continue until lawful opening of the same house.

Healthy members of the household were shut up with the sick, so you got to basically sit there and wait to die:

This shutting up of houses was at first counted a very cruel and unchristian method, and the poor people so confined made bitter lamentations. Complaints of the severity of it were also daily brought to my Lord Mayor, of houses causelessly (and some maliciously) shut up. I cannot say; but upon inquiry many that complained so loudly were found in a condition to be continued; and others again, inspection being made upon the sick person, and the sickness not appearing infectious, or if uncertain, yet on his being content to be carried to the pest-house, were released.

It is true that the locking up the doors of people's houses, and setting a watchman there night and day to prevent their stirring out or any coming to them, when perhaps the sound people in the family might have escaped if they had been removed from the sick, looked very hard and cruel; and many people perished in these miserable confinements which, 'tis reasonable to believe, would not have been distempered if they had had liberty, though the plague was in the house

If you were lucky, you might be able to find someone to nurse you. They were normally poor, older women, desperate enough to risk the plague, and the quarantine period:

If any nurse-keeper shall remove herself out of any infected house before twenty-eight days after the decease of any person dying of the infection, the house to which the said nurse-keeper doth so remove herself shall be shut up until the said twenty-eight days be expired

The symptoms were ultimately pretty horrible though: high fever, delirium, the classic swellings (buboes - i.e. bubonic plague) in armpits and groin. If you "came down" with the plague, you had to hope that your fever "broke"/subsided. Otherwise you'd go into shock and die:

It is most certain that, if by the shutting up of houses the sick had not been confined, multitudes who in the height of their fever were delirious and distracted would have been continually running up and down the streets; and even as it was a very great number did so, and offered all sorts of violence to those they met, even just as a mad dog runs on and bites at every one he meets; nor can I doubt but that, should one of those infected, diseased creatures have bitten any man or woman while the frenzy of the distemper was upon them, they, I mean the person so wounded, would as certainly have been incurably infected as one that was sick before, and had the tokens upon him.

I heard of one infected creature who, running out of his bed in his shirt in the anguish and agony of his swellings, of which he had three upon him, got his shoes on and went to put on his coat; but the nurse resisting, and snatching the coat from him, he threw her down, ran over her, ran downstairs and into the street, directly to the Thames in his shirt; the nurse running after him, and calling to the watch to stop him; but the watchman, frighted at the man, and afraid to touch him, let him go on; upon which he ran down to the Stillyard stairs, threw away his shirt, and plunged into the Thames, and, being a good swimmer, swam quite over the river; and the tide being coming in, as they call it (that is, running westward) he reached the land not till he came about the Falcon stairs, where landing, and finding no people there, it being in the night, he ran about the streets there, naked as he was, for a good while, when, it being by that time high water, he takes the river again, and swam back to the Stillyard, landed, ran up the streets again to his own house, knocking at the door, went up the stairs and into his bed again; and that this terrible experiment cured him of the plague, that is to say, that the violent motion of his arms and legs stretched the parts where the swellings he had upon him were, that is to say, under his arms and his groin, and caused them to ripen and break; and that the cold of the water abated the fever in his blood.

People would sometimes hurt themselves in their delirium:

It would pierce the hearts of all that came by to hear the piteous cries of those infected people, who, being thus out of their understandings by the violence of their pain or the heat of their blood, were either shut in or perhaps tied in their beds and chairs, to prevent their doing themselves hurt—and who would make a dreadful outcry at their being confined, and at their being not permitted to die at large, as they called it, and as they would have done before.

The worst thing was, if you did die of the plague, it sounds like you had about an hour of lucidity so that you knew exactly what was happening to you:

This running of distempered people about the streets was very dismal, and the magistrates did their utmost to prevent it; but as it was generally in the night and always sudden when such attempts were made, the officers could not be at hand to prevent it; and even when any got out in the day, the officers appointed did not care to meddle with them, because, as they were all grievously infected, to be sure, when they were come to that height, so they were more than ordinarily infectious, and it was one of the most dangerous things that could be to touch them. On the other hand, they generally ran on, not knowing what they did, till they dropped down stark dead, or till they had exhausted their spirits so as that they would fall and then die in perhaps half-an-hour or an hour; and, which was most piteous to hear, they were sure to come to themselves entirely in that half-hour or hour, and then to make most grievous and piercing cries and lamentations in the deep, afflicting sense of the condition they were in.

To summarise, a day with the plague would be terrifying and horrifying. If you were a bit ill, you would be frightened that you had it and trying to hide it in order to avoid getting shut up, and having your family/household servants etc. shut up with you.

If you were able, you might be able to find yourself a live-in nurse, but there's little that they would be able to do other than mop your brow and, if necessary, tie you down to stop you running amok/injuring yourself in fever. If your symptoms got really bad, you'd be in horrible pain, with horrible swellings and/or oozing sores in your armpits. You'd also be shut up in your house which, in the days before readily-accessible windows, plumbing and ventilation would be quite dark and airless, not to mention malodorous. If you were actually dying, you might be delirious for most of it, but you got some time right at the end to really appreciate what was happening to you.