Your son got a similar illness of Gastroenteritis
Give sips of oral rehydrating solutions like Pedialyte
to prevent dehydration
. And you can give sips of coconut water, lemon water.
Continue Tylenol for fever in prescribed dosage.
Watch for signs of dehydraton like dry tongue and mouth, decreased activity and decreased urination.
Consult your Pediatrician
immediately if you find any signs of dehydration.