If you can't stop- it's not a habit: it's OCD (Obsessive Compulsive Disorder) it's a brain wiring glitch that usually happens (just) prior to puberty. Whatever the newly acquired habit, it gives a boost of pleasure chemicals to the brain, making it hard to stop; whether it's nail-biting, cutting, spitting, counting, hair pulling: whatever. It becomes a form of self-soothing, too. Though as you've noticed, it doesn't come without a long term price tag.
But, the fact that your issue has such a destructive quality to it, similar to cutting- means Anyone with any sense would have to recommend professional help. Not only because you're at increased risk for oral cancers and other creepiness, but because this OCD might take an even MORE harmful twist, and you'll want a Dr. already on your case. Get help now. Talk to your primary care provider.