Hi.. Thanks for writing to us.. Well, due to cheek bite, your mucosa has torn leading to formation of a traumatic ulcer.. It is a common cheek bite lesion and nothing serious.. You can even feel a bump in that place but it is a normal finding with such kind of cheek bite injury. No need to worry about it as it will heal gradually. If it is painful then you can apply pain relieving gel like Oragel, mucopain gel etc over it, or other commercial products that contain Lidocaine or Choline Salicylate. Continue doing warm salt water gargles and avoid spicy foods. You can hold a cube of ice over that place to reduce inflammation and pain. It will get better in 4-5 days.. Hope you get well soon.. Regards.