Mouth cancer from tobacco?

A little over a month ago, i tried chewing tobacco with my friend, then later in the day i tried it again, I never did it before or after. The next day i looked at my gum jus tto see if there was any marks and I found a black dot, about the size of a pencil tip, on my gum. I dont know if its been there and I just havent looked at it, or if its from the dip. I've tried brushing it away, and even tried to scratch it off with a needle but its still there. Been a month, hasnt grown. What is it?