I keep biting the inside of my mouth when chewing. Does that mean I have to fix my bite?

Seek dental consult. Cheek biting could indicate a lack of a stable, repeatable chewing motion, which often can be related to bite problems including crossbites and premature tooth interferences. Repeated traumatic injuries to the lining of the cheek can lead to more serious problems. It is prudent to consult a dentist for an evaluation.