Thank you for your query.
It appears that your son has developed aphthous ulcers
on his tongue. You are giving him the right medicine and continue doing so. You may make him do mouth wash with Listerine
in warm water two three times a day for some relief. You can also apply glycerine over them.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal