Thank you for your query,
Your child seems to have gastritis
mostly due to a virus.
You can give one antiemetic like ondansetron
in prescribed dose.
And start giving oral rehydration solutions like Pedialyte
, coconut water, lemon water.
Monitor his hydration by his activity, urine output, moisture of tongue.
Consult your Pediatrician
for further assessment and for the specific treatment.
Hope I have answered your query.