C.G.
Could be a gazillion things.......are you pregnant?
If that's a no I'd wonder if your gall bladder is shot. Best advice is get in and see your doctor.
Sick to stomach can range from those above to all sorts of GI issues: IBS, diverticulitis, colitis, etc.
If nothing else, lay off all dairy, wheat products, fake sugar, caffine (soda, chocolate, coffee, etc), red meats. These are some of the hardest foods to tolerate/digest.