I have a reocuring ulceration on the roof of my mouth. I'm not sure if it's viral or bacterial. It reoccures ever couple months. It starts out as a red, inflammed sore on the roof of my mouth, and then progresses into some form of an ulcer, or lession. I can usually get rid of it by hitting it hard with listerne three times daily, but recently, I became reinfected with it, and this time, it looks like the Grand Canon on the roof of my mouth with a black spot in the center of it all. This is what began to concern me. It's not responding to the listerene like it use to. I am a smoker. I'm not sure what to think....... Any suggestions? I don't think it's cancerous due to the reptitious activity of it. (Coming and going).