For those of you who suffer with these horrible nasties, I would suggest trying a small dietary change and that is to refrain from eating chocolate, even small amounts like in desserts etc. I cannot believe it yet but I had an almost immediate response to this small change. I was not a big chocolate eater, just occasionally. It may not work for everyone but definitely worth trying for at least 3 months.
I have suffered with ulcers for over 60 years. The technical name is "Apthous ulcer". The medics had no answer and I have been looking for answers myself, using self diagnosis, different vitamins, different foods, (except chocolate) everything you can imagine that would give me answers. Three years ago, I was diagnosed with a mild form of Crohn's disease. However after initial treatment where I regained my general health I still had on going ulcers. As a treatment in the intervening period the best medication is "Kenacort" paste made by Abbott Labs.
Good luck