See below. The cause may be an inner ear infection, an infection of the ear canal, etc.
Depends. Ear infections of the skin of the ear canal or middle ear can both cause pain. In adults that do not have infection, TMJ irritation is a common cause of sharp ear pain that may be intermittent.
TMD. You may have temporal mandibular joint dysfunction. Have it evaluated by a dentist to determine the cause. It may be due to sleep apnea.