On Monday I had this sore on my gums. It is located on my gums right under my last maular on the bottom left side of my mouth. I never looked at it the day I got it. But on Wednesday I checked it out. And it basically looked like a really long (about as long as 1 and a half maulars) canker sore, but it had a black line right down the middle of it. The next day it was half split open, and now it is a completely split open gash in my gums. I can barely eat, every time I open and close my mouth it stings. I can't lay my head down on the left side. Now it is not as inflamed as it was yesterday, but it is still equally as painful. If I put pressure on my left cheek I can definitely feel the soreness. What the hell is this thing? Is it really a split open canker sore? Or something worse? I do smoke cigarettes. 2-8 a day. I do not drink. I don't drink excessive amounts of acidic juice. Nothing really abnormal about my lifestyle. Any ideas?