Facial pain can be caused by a variety of reasons.
A good method to help your doctor diagnose what's wrong is to keep a pain journal. List when the pain happens, how long it lasts, how would you describe it, what parts of the face are affected, does anything seem to trigger the pain, have you had any recent injuries.
Have you seen a doctor about the pain? Have you had any diagnostic tests? If so, what type and what were the results?