Are you feeling OK?
My stomach is bothering me.
What have you been eating?
I had a ham sandwich with mayonnaise for lunch.
Maybe the food had something wrong with it.
It could be bad food, but I didn't feel so well yesterday, either.
Have you been under a lot of pressure lately?
I haven't been under any more stress than usual.
Perhaps you have caught that bug that is going around.
I feel like maybe I am coming down with the flu.