When my chidren were around the age of yours I would boil some rice in extra water and give them the water to drink. I'd add a little sugar or honey to make it taste good. The rice water seems to help with the diarrhea. I'd also give them mashed bananas and 7up or Gingerale at room temprature. The most important thing is to keep him hydrated. They can get dehydrated so fast at that age. So give him as much as he wants to drink and whatever he will drink or tolorate. Different teas with some honey are also really good.
