Hello pls check if it is keratitis linear Alba suggest u do not go into self diagnosis. Due to a tight around the mouth musculature and prominent cheeks these type of bite are common. U can use a metrogyl gel and get teeth examined. Again fibrous is a very harsh self diagnosis.
Next Steps
Pls consult a dentist to avoid panics
Health Tips
You can google your symptoms but pls do not self diagnose.