I don't know what it is in Gatorade or pedialyte, but I get gastro problems
with them, so it might be the drink.

If he can eat them, try the BRAT diet - banana, rice, apple and toast. And
small sips of water. The banana will give him the potassium and such that is
present in the pedialyte.

Good Luck. It's always hard to have sick kids.

Cindy B.