Phrodeau gives excellent advise! I would only add that you need clear liquids, such as Sprite, 7UP, water. I had a horrible bout of food poisoning once and the doctors who treated me said clear liquids are the ONLY thing you need to be taking in when you have tummy problems.
I have a most excellent recipe for a celery and garlic soup that I always make for myself or the hubby at the first sign of a cold. Is easy, cheap and works great. PM me if you want the recipe.