How to quickly prevent an almost inevitable mouth ulcer?

Ok. I get a lot of mouth ulcers. Mainly because I bite the inside of my mouth by mistake. I went to my doctor and asked him why I get them when this happens and he said some people are probe to getting them and also maybe bacteria in my mouth. Anyway he gave me antibiotics to prevent me from getting them again for a while (about 3 months he said). These antibiotics haven't worked because I've got about three mouth ulcers since I was given the medication (1month ago). He also gave me paste to put on them if I get them but that didn't work either. Anyway seeing as biting the inside of my mouth always leads to me getting an ulcer, I was hoping I could prevent this broken, raw gum or inside if my mouth( inside the cheek) from turning into an ulcer... Please help. I need it to heal in the next week. Also bonjella doesn't seem to work either. :) any suggestions appreciated.