How do I cure my disease?
Receive any blessing from any God in a Temple, and you get all diseases cured. Examples are the Shrine of Talos and the Temple of Kynareth ((Whiterun)
If you go to the Brawny Prawn in Riften, you can buy a Cure Disease potion that'll do the job as well.
The Brawny Prawn is beside the Bee And Barb to the right of it.
In the town of Riften, you can visit the Temple of Mara. Go inside the temple and activate the Shrine of Mara, in the front-center of the temple. That will cure your diseases, and people will stop telling you that you look sick.