Why do i bite on my cheeks all the time.?

Bad habit: You are probably a bruxer, which means you are grinding your teeth. Look for a white line on the inside of your cheek where your teeth come together, possibly also a scalloped shape on the outside edge of your tongue. Both indicate that you are subconsciously clenching or ginding your teeth. See your dentist, you probably need a bruxing appliance.