The most common type of ear infection is called otitis media. It is caused by swelling and infection of the middle ear. The middle ear is located just behind the eardrum.
An acute ear infection starts over a short period and is painful. Ear infections that last a long time or come and go are called chronic ear infections.
>The ear infection may start shortly after a cold. Sudden drainage of yellow or green fluid from the ear may mean the eardrum has ruptured.