Dear Bailer - I'm so glad you've decided to quit. It is no fun at all having to go thru cancer surgery and radiation or chemo treatments. It affects your whole family. There is a guy (Outdoor Texan) who has posted here and also speaks to teens about his quitting dip. You'll get lots of information at his site:
http://www.outdoortexan.com./mycancer.htm
As to your question, if you already have a red sore, in your mouth, it's best to get it checked out so that you know for sure if it is cancer. There is a whole lot of information and knowledgeable and compassionate people here that can help with whatever questions you have. Let us know what happens.