Your son probably has what my two year old just got over. It's a nasty virus from the enterovirus family. it causes flu like symptoms as well as viral gastreonitis. In other words, its a "stomach flu" It can last from 3-5 days or 10-14 days depending on how well you treat it. These instructions that I am about to give you are directly from my childs pediatrician and also from my experience. You must get your son to drink plenty of pedialyte solution. Only samll sips at a time. Too much fluid at once with upset the intestines. The child must have three ounces after each loose stool. Make sure he goes through at least two bottles in a 2-3 day span. It is a must that he drinks the pedialyte, because it is the only thing that will prevent dehydration in a small child. Water will not prevent dehydration.If the child gets dehydrated, he will need to go to the hospital for IV fluids. Signs of dehydration are sunken eyes, little or no urine, white tongue, lathargic and weak. DO NOT FEED THE CHILD ANY MILK, OIL OR EXCESSIVE SUGAR. especially no dairy, it will make the virus worse. Feed him bland foods for the next 7-10 days. Even after you think the virus is over, it can return if you go back to a regular diet too soon. After the pedialyte is done, only have him drink clear fluis but no juice, nothing that will cause a loose stool. Make sure you wash your hands each time you change him, the virus is highly contagious. Another name for the virus is the rhinovirus. BEWARE....GOOD LUCK
PS.
Children hate pedialyte solution, it taste salty. Youcan be creative and mix it with a little ginger ale to cut the taste, but he must drink it, lots of it. I had to force my daughter. It's actually the thing that he needs the most to get over this.