Whenever i have a belly ache, After i throw up i feel better, i'm not telling you to like force your self to puke or anything, but if your stomach is upset then you might end up vomiting. It'll problably feel better in a little better naturaly unless its something more serious like the flue or something. Just rest, drink plenty of liquids, stuff like gatorade if you have it to hydrate you incase you throw up.
But also try an over the counter stomach medicine. Ask the pharmasist at a drug store what they reccomend.
Hope you feel better.