When you talked about abscess I was thinking maybe something enclosed and buried in the jaw at the root of a tooth - something which was contained and invisible but perhaps can be felt as a lump.... but does your vet think this is an
open wound (an ulcer) on the inside of the cheek? Did he recover OK from his original dental surgery and put weight back on or has he been having problems ever since?
Sometimes if an ulcer forms on the inside of the cheek it can be caused by a 'tooth spur'. This is a little pointy or hook-like bit of tooth that digs into the cheek and makes chewing painful, so they eat less - especially the tough stuff like hay that needs hard chewing - then the teeth start to overgrow and the pig finds it even harder to eat. Sometimes little sharp spurs right at the back can be missed during a dental - even under anaesthetic - my vet says there is usually a bit of food in the cheeks
all the time so they can be easy to miss. Vets look to file teeth surface down on
top to make a good chewing surface and they look to see if the tongue is trapped by the back molars growing
inwards - they can file to release the tongue, but they can sometimes miss a little sharp spur on the
outside next to the cheek because the mouth is small and the cheek muscles are huge! When piggy comes round and starts trying to eat again they have better teeth for chewing but if a little spur is there it will still rub and the problems begin again.
I have seen x-rays on here showing a tooth spur but only big ones - I don't know how easy or hard they are to find on the teeth with examination or x-ray. There was one on the x-ray in one thread which was massive - almost as big as a tooth and sticking out sideways so it was very easy to spot even for an amateur like me. But if I had a piggy with an open sore on the soft flesh of the cheek inside the mouth that is the first thing I would suspect. Antibiotics will treat the infection and painkiller will help but if there is a spur this problem can come back again. Check with your vet that they had a very careful look for sharp little spurs on the outside of the teeth when they did his dental.
Most of all,
really well done for all your effort. Dental pigs are heart breaking sometimes as piggy's favourite thing is to eat all the time and it makes us feel so sad when they struggle. You are such a dedicated owner to make such plans and doing the best for your piggy. He is lucky to have you to care for him during his problems and he must trust you a great deal to help him eat