I bite the inside of my mouth and sometime the skin peels off. is that bad?

Trauma to cheek: Biting your cheek to the point of skin peeling may be a compulsive behavior. Continually traumatizing the cheek mucosa can lead to changes in the tissue that are abnormal. If you have recently had a filling or crown placed perhaps the cups are a bit too large. Check with your dentists asap to see if there is an easy fix to the problem.