Thank you for your query.
Your son has gastritis
Give him small feeds at regular intervals.
Give him anti-acid medications daily for 10 days.
Give him antacids for the pain.
Avoid hot,spicy,sour food stuffs.
Give him some rest and lots of fluids.
Hope this answers your query.
If you have any other queries kindly direct them to me.
Wishing your child a speedy recovery.
Have a nice day.