Burning sensitive mucosa behind upper wisdom tooth. jaw and ear pain. no tooth pain but do have cavity in that tooth. no redness. what causing this?

Infection ?: If the cavity is near the gumline, the acids and bacterial toxins can be irritating the mucosa. See a local dentist ASAP for treatment to prevnt the problem from escalating.

See your dentist: When wisdom teeth cause problems, they need to come out. If you are experiencing pain, swollen gums, lymph nodes and it does not go away or if you find it difficult to open your mouth, you should see a dentist for evaluation, x-ray and wisdom teeth removal.