I have this problem as well. Recently, I've been randomly biting my cheek, and occasionally my tongue, when I eat. Kind of food doesn't seem to matter (this last time I was eating cottage cheese). Very frustrating, and painful. I also have long covid (have had it for several years now) and I believe it started AFTER I contracted covid. I also have some severe back issues which have been causing some inflammation. I have to believe there is some physiological cause to this other than my teeth, which are fine - I have no other teeth or mouth or jaw issues and nothing has changed in them for a while.