I would stress dose your son, but I would not do the Immodium without talking to a pediatrician. You would be assuming that this is a virus, and you don't know that. Persistant diarrhea can be a serious thing, and using something that stops the peristalic action can be dangerous. You want whatever is causing this to be excreted from his body. If you think your son needs to be looked at, take him to the emergency room. Don't be intimidated by your endo. This is your son, and you know him best. How is he acting? Is he lethargic? Does he act normal between episodes of diarrhea. Is the diarrhea bloody or does it have mucous in it? Color and consistency do not matter as much as the presence of blood or mucous. My daughter had this about two months ago, and it lasted for six days. Two of those days were severe. Her endo said "give the stress dose. When in doubt, give it. You can't hurt her by stress dosing in a situation like this." If your son begins vomiting, I would take him in. Good luck, and God Bless.