It could be an infection or even heavy wax buildup in the ear canal, or any number of other things.
We can guess, but you should see your doctor for a real diagnosis and treatment if needed.
Its common for ear infections to have referred pain in the jaw and mouth area. Another possibility that is often overlooked is that you have an oral infection with referred pain to the ear.
I also want to add that its possible for an infection to start in either area and speak to the other.
Some common bacterial infections of the mouth that do this are actinomyces, streptomyces, nocardia and some of the spirochaetes.
These are usually easily treated with antibiotics and possible drainage/removal if there is an abscess.
Good luck to you and please keep us updated on your recovery.