People keep telling me i look sick but have no idea on how to cure it..

Drink a CURE DISEASE potion. Any alchemist will sell you one or you can mix some Vampire Dust and Mudcrab Chitin to make your own.
Illnesses will show up under your ACTIVE EFFECTS, in the Magic Skill section.

If people are telling you that you look sick, you might have vampire disease...so don't wait around, I'd say ; )

As mentioned, cure disease potion or just visit the altar in any temple or even the outdoor altars and pray at the altar. voila. cured.

Activate any of the 9 Shrines which can mostly be found at Hall of the Dead or Temples in major settlements.

Go to a shrine which will cure your diseases. There's an easy one to get to in whiterun, and there's also one at fort amol if you're scared of crowded populated places.
I get that comment alot, too, and as far as I can see there's nothing wrong with me. It may just be another sly comment generated by the NPCs. I get it alot from alchemists oh shock the people who sell cures.

A potion or praying will work.

Thank you guys!!