Robbie,
Have you been getting thorough oral cancer screenings from your dentist? I won't tell you not to chew, but I will tell you that you need to go to a dentist that knows how to do a thorough oral cancer screening. Check out SextetScreening.org (6 steps to a thorough oral cancer screening) to know what you should be getting.
It would be helpful for you to have a dentist that has an intra-oral camera. This way, you don't have to remember what your ulcer (or any other area of irregularity) might have looked like 2 weeks ago, you can have a photo taken. (The camera costs about $800 - not a huge investment for a dental practice).
You are the only one who is in charge of your health.
You have a choice to sit back - or to be sure you get the best care so that if you have a oral cancer, it is caught early, and thus very curable.

Questions to ask the dental office secretary:
1-When did the dentist last have some continuing education on the early detection of oral cancer? since I chew, I'm at a higher risk and need to know.
2-Which hygienist in the office do you recommend for the most educated oral cancer screening? and why?
3-Do you have an intra-oral camera?

Good luck.
Eva