NPC's keep saying that I look sick. My stat screen shows no poisons/diseases/etc. I drank a cure disease, and people are still saying this. ?

Check the magic section for active effects.... You got something - grab a cure disease potion and drink up!

I have had this happen, usually it is Poison that triggers it as that is the only thing I remember ever seeing pop up in battle. I just go to a shrine and get a blessing whenever I see one.

Negative. The OP already said they checked their active effects and found nothing. It's actually nothing more than the shopkeeper trying to sell you stuff. Kind of a funny joke on Bethesda's part.

"You look a little pale."

The alchemist in Whiterun says this to you even when you are not sick. It is part of her role as she is trying to get you to buy some of her potions.

Ha!! That's exactly who's saying it. Funny.