You are very smart to pursue this as it sounds as if whatever it is, it is at an early stage. Make sure you get a biopsy of the area or some other test that will conclusively prove whether or not it is anything to be concerned about.
I am a tongue cancer survivor; had what seemed like a tiny (almost invisible) canker sore on the side of my tongue that didn't go away. I had it removed after having it for several weeks. It was cancer, and I had to have an additional piece taken off of that side of my tongue to make sure they got it all (which they did). I am very lucky and have no effects from the surgery and (knock wood) no recurrence after nearly 3 years.
Please let me know how you're doing and what you found out at the doctor. I know addictions s*ck but be sure to be honest with the doctor about using chewing tobacco and drinking. I was a kind of heavy drinker (2-3 glasses of wine a night on average) and I quit cold turkey after I found out I had this and haven't touched it since. Alcohol is indeed a risk factor for oral cancer, and in combination with tobacco it's even worse. I had also smoked in the past but had quit 25 years earlier so I do not think in my case the tobacco was a factor but you never know I guess.
Best of luck to you - and if it isn't cancer this time, it could be another time, so please, please, try to quit the tobacco. Chewing tobacco is one of the biggest risk factors out there.