Enflamed upper mouth on retic

[bstein54]

My 8ft retic has had a swollen upper mouth for about 5 months now. I have raised and lowered the humidity as well at the temperature of his enclosure and it has made no difference and brought him to the vet that treats reptiles twice. On the first visit the vet opened his mouth and there was a little white substance where his tooth is located. He scraped it off and attributed it to a broken or loosened tooth which made me recall that around the time I noticed the swelling, my uncle had told me the snake struck at the glass when he walked in my room one day. Could it be a broken bone in his face or broken tooth that is still lodged in his mouth? There were no other signs of a bacterial infection or anything like that so he said to just give it time. He gave me an antibiotic which made the swelling decrease but never fully go away. I went back to the vet maybe 6 weeks later and again he said to try another round of the antibiotic but the result was the same. My retic hasn't lost his appetite at all but every time he eats his mouth swells up a ton and never fully goes away.
Any thoughts or suggestions would be much appreciated, thanks.