HI, thanks for using healthcare magic
The most important aspect of your son's treatment is management of his fluid intake to prevent dehydration
which can commonly occur in children with gastroenteritis
Signs and symptoms of dehydration are: decreased urine output (decrease in the number of wet diapers you have to change), dry skin, elevated heart rate
or decrease in conscious level, tenting of the skin (when it is pulled up, it stays in that position because of lack of fluid in the skin), crying with no tears.
It is important that he is given fluids to replace what he is losing by vomiting
. The best fluids would the oral replacement fluids such as pedialyte
which would contain water and the electrolytes that he needs. He may not want to use alot at each time and actually giving too much at once may cause him to vomit. Normally it is recommended that a small amount (a tbs for example) be given every 5 minutes.
If he does not tolerate the fluid by mouth then it may need to be given by iv by his doctor.
In addition to fluid replacement (the most important part), you can try to use of probiotics which have been shown to reduce diarrhoea.They may be found in some yogurts or on their own at some pharmacies.Avoid any solid food at present as well as any milk products which may make the diarrhoea worse.
At his age ,it may be best to take him to his doctor so that his fluid status can be assessed and the exact amount of fluid needed to rehydrate him and continue normal function, be calculated.
His appetite will return when he feels better.
I hope this helps