Treat Your Upset Stomach

To treat your upset stomach, use peppermint tea leaves. Pour one cup of boiling water over a heaping tablespoon of peppermind tea leaves and steep for 5 minutes. Drink a cup of this tea between meals, but no more than four cups a day. Menthol oil in the tea is responsible for the soothing effect.

Caution: Don't give peppermint to children, as menthol can give them a choking feeling.

Stomachache

Drink cup of chamomile tea 3-4 times a day until you feel better.

Even for kids it works, I give chamomile tea to them when they have stomachache that doesn't go away.

Another receipe that also usually works.
Lassi (a yogurt drink) is also used to ward off gas and bloating.
1 cup room temperature water
¼ cup yogurt
1 pinch dry ground ginger
1 pinch ground cumin seeds
1 pinch salt
Blend for a minute and drink it after meals. It is also a very refreshing drink especially during summer time.