ear/tooth problem

Question
My cat is just under one year old. He was a stray and about a month old when we found him. About 5 months ago he started having chronic ear infections and started scratching under his chin so badly that he scratched all the hair off and made his chin and ears bleed. He did not have ear mites or fleas. About three months ago his adult teeth started to fall out and he developed bad gingivitis around his gums. My vet gave him a cortisone shot which made all these symptoms go away completely for about a month and a half, now they are all returning. I am aware that they could be allergy related, however he had been eating the same food for the previous 4 months with no problems at all. He has had no loss of appetite or energy. He does drink a lot but i believed that to be because his jaw is slightly deformed from where he had been attacked by the neighbors dog when we found him. his jaw does not close all the way. Is there anything other than allergies that explains these symptoms?

Answer
He is a little young for allergies, so I would have to say that pain is the problem.  If there was poor healing in the jaw, then there may be chronic inflammation and pain.  The steroid shot reduces inflammation and he may need a shot periodically.  CAts are pretty tolerant of steroids and rarely have side effects.