S.C.
W., I'm sorry your son is sick! It's so hard to see our babies like that. The best advice I have for diarrhea is to feed him yogurt twice a day, or if he won't eat it, get some acidophilus milk, which has the same active cultures in it. These will replenish the "good" bacteria in his stomach, and help his tummy regulate itself. That, and the good old BRAT diet - bananas, rice, applesauce, toast - are easy for a tummy to digest when it's been sick.
I hope he's feeling better soon!