Try a "cure disease" potion or ingredient that has the "cure disease" effect. Some of the temples cure diseases by praying at the main altar (I think the one to Mara does)
God **** I cant figure out where or how to get this disease off me, its ********. This is one of those few things that makes you ask, why the **** did the designers put this in. Itd be ok if you could sleep it off but apparently not, its just a super annoyance and I cant figure out how to get rid of it.
Never mind I found out how to, you have to go to a temple and click on the shrine to get rid of diseases. Kind of a ******* till I finally found a temple.