This looks to me like it’s from [Bodleian Library manuscript 264, “The Romance of Alexander”] (http://image.ox.ac.uk/show?collection=bodleian&manuscript=msbodl264) illustrated by the Flemish illuminator Jehan de Grise and his workshop, 1338-44. The image is typical of the whimsical marginal illustrations found in thirteenth and fourteenth-century manuscripts. The fiddler is not as all unusual for the marginalia in Bod. 264, which has lots of musicians and dancers. The contortionist may have some meaning I don’t know, but I suspect it’s just the artist having fun. In religious manuscripts these kind of fantastical images sometimes have a coded or allegorical connection to the text but here it’s probably just a parody of a dancer or acrobat--very much in the style of the artists who made this book.