Don't know for sure, but that sounds like how my son was when he had Rotavirus. He started out vomiting at daycare, and continued that whole night at home. The Dr. said to stop giving him anything for 12 hours to let his stomach settle down (he was keeping nothing down), and then an ounce of pedialyte an hour and slowly increase. Well, the diarrhea started the next day, and then a fever started that night (only 101.5). I woke up at 5 am the next morning, and his temp was 106, so we went straight to the ER. Watch and make sure he doesn't develop a fever, or get dehydrated. As long as he doesn't have either of those, I have always been told my doctors that they don't get too worried for 2 weeks. Give him things like rice and bread that are gentle on the stomach and help bind, and there is also a formula that they gave my 2 1/2 yr old son this summer (he had dirrhea for almost a month... no cause found), called similac isomil DF, it is a soy formula made for diarrhea to help bind it up, and it worked for my son. The only place I have found that it is available is Walgreens, and it only comes in 32 oz. ready-to-use bottles. Ask your dr if you should try that, it helped him a lot. The biggest problem I ever ran into with diarrhea was a rash, but if I kept him covered with petroleum jelly after every diaper change, he usually didn't get one at all. Good luck, and I hope your son is better soon! Sick kids are not fun... especially if they get a bad rash... and scream for every diaper!
J.