When you have an upset stomach you should drink at least some water to keep yourself hydrated.
Drinking Ginger Ale, Sprite, 7 Up and even some orange juice or apple juice.
Having some warm tea and even drinking some Pedialyte can also help and the Pedialyte will replace lost electrolytes in your body when you lose the electrolytes due to diarrhea or vomiting.
As long as you avoid any dairy products and drink anything else then your stomach should be able to settle and you should feel better within a few days.