Real people fall ill. It's likely that people in alternate realities - fantasy, alternate history, the far future, whatever - do too. So they trundle round to the doctor or local wise woman, or plug themselves into a medi-analyser, and want to know what the problem is.
So here is a simple list of an hundred assorted ailments. Most (if not all, some I haven't heard of) are real world diseases or infections. All you get is the name, so if you do not know what it is or want to know what the character needs to get better, you'll have to do a spot of research. You may find some of them quite inappropriate given the victim and their circumstances - or that incongruity might become the key to your whole plotline, or you may prefer to read through the list to get inspiration rather than rolling dice.
A handy resource, but unless the ailment is only a passing mention (or you have some medical knowledge) you'll need to research the diseases if any description of symptoms or cures are required.