The most common cause of earaches is related to ear infection. There are two types of ear infections, one involving the external ear, which involves the outer ear and the ear channel leading to the eardrum.  The ear channel leading to the eardrum is approximately 1 inch in length and sometimes can be injured by the use of instruments to remove wax, causing a perforation of the eardrum.

Outer ear infections, which are sometimes called swimmer’s ear, are also a cause of earache.  This commonly follows swimming in either the swimming pool or in contaminated water.  This causes severe swelling and pain in the outer ear, and the hearing is sometimes impaired.

Middle ear infections are slightly different in that there is no pain on the outer ear, but there is deep pain involving the eardrum, and in these cases this is usually accompanied by severe hearing loss and fullness of the ear.

Another cause for earaches is called temporomandibular joint disorder, which is related to the inflammation of the joint in front of the ear, which is the same joint where the jawbone hinges.  This can be related to other forms of arthritis as well as injury to the jaw. 

All the above conditions require the assistance of a physician for diagnosis and treatment.