Both my mom and physician recommend drinking a room temperature, lime-flavored beverage such as 7UP, for a tummy ache.
From what I know fizzy drinks, work opposite and usually upset stomach. They probably forgot to tell you that the drink need to be flat.
Sounds similar to the one I know with Cola.
For upset stomach there is one easy remedy: de fizz some Coca Cola regular, ( this can be done by adding a teaspoon of sugar) and sip a spoonful each hour.
For colds (incl.sore throat and runny nose) : mix red (any) + herbal( comomile or mint) teas and add fresh lemon, sweeten with honey (optional) . Drink it every day as much as you like.
Or make a drink, which I call "shock dose of vit.C":
to 1glass of very warm water (but not too hot) add lemon juice (from half a lemon or 2/3 if small) , you can sweeten it with honey or sugar (optional). Drink it only for a night or while at home because afterwards you sweat so much, you'll need to change your clothes. Next day you should feel like a newborn.