Brief Answer:
Less likely to be related to the medicine.

Detailed Answer:
Hi
Welcome
I have gone through your query.
I would like to know since when he is facing this problem?
Does he have cold, sore throat, tonsillitis? Is there any change in the voice?
Is there any swelling or redness of the tongue?
Is there any ulcerations in the tongue?

To my knowledge I am not aware that the drug prescribed is responsible for the symptoms that you have mentioned.
Symptoms may be due to tonsillitis, local injury to the tongue which might have occurred during chewing, GERD may it self can be responsible for this even though less likely.
Presently I would suggest him to go for warm salt water gargling three to four times a day. Observe for any local lesion , get it examined by the local doctor or dentist.
I advice you to Eat smaller, more frequent meals to avoid eating too much in one sitting.Avoid spicy food, smoking and drinking. Lose weight if you are obese. Raise the head of your bed by four to eight inches. This allows gravity to help keep your stomach’s contents where they belong. Eat meals at least two to three hours before lying down on the couch or bed, and avoid bedtime snacks.
Hope this helps
Take care

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