Thank you for your query.
I understand your concern.
Please stop all milk products,fruit juices and wheat products for 2 weeks.
Give him rice based products and chicken gruel.
Get a stool test
done and a coeliac
Give him probiotics and antispasmodics.
Hope this answers your query.
If you have any other queries kindly direct them to me.
Wishing a speedy recovery.
Have a nice day.