What can it be?

[Kseniaksu]

Good afternoon everyone!
Tell me, please, what can it be.
One morning I wake up, and I have a rough mucous cheek! This roughness goes only along the bite line with separation. Sometimes it becomes more rough, sometimes less. Sometimes reoccurrence occurs. I've been to 2 dentists and they didn't say anything. Please tell me what it could be) there are no white spots or anything like that

 

[Kseniaksu]

 

[Dr M]

Might be related to grinding or clenching at night when you sleep. Nothing to worry about at this stage, but you can consider buying an over the counter night guard to sleep with, or if you have severe grinding, consider having a hard bite-plate made at your dentist.