Medication I’m not sure but I used to experience burp also until I started practicing some simple taichi routine few years ago. It works for me but not sure if it works for your uncle. This was an accidental discovery, I dont purposely learn taichi to ease burp but I”m learning because my the late grandfather was a taichi practioner & I”m picking up on same interest few years back. It just dissappear naturally , instead of burp , now the gases are release through fart.

is he a heavy coffee drinker?