Bite mark in inner mucosa of lower lip still have even after 4yrs,got irritating numb after active sex,how does it still have and how i can cure?

What kind of bite: what kind of bite we are talking about human bite or animal bite was it treated four years ago by a doctor or not if it was a human bite did start during or after sex are you sure what you have is a scar from old bite or an ulcer resemble scar you might be having STD like herpes on the mouth too many possibility my advise go and see a doctor good luck