Earache: Pain in the ear. This can occur because of conditions within the ear itself, the ear canal, or the visible external portion of the ear. Acute infection of the middle ear, medically called acute otitis media (AOM), is inflammation of the middle ear and is the most frequent diagnosis in sick children in the US. The eustachian tube is shorter in children than adults which allows easy entry of bacteria and viruses into the middle ear, resulting in acute otitis media in childhood. Infection of the ear canal (otitis externa) is also called swimmer's ear. Otitis externa is typically caused by bacterial infection. Earache can also be due to pain and inflammation of the outer portion of the ear.