My mother has developed otitis media. What is it exactly?

Middle ear infection. The middle ear is the (normally) air filled space behind the ear drum. A middle ear infection (otitis media) usually starts with a cold or allergies. Fluid builds up in the middle ear space then becomes infected. Depending on the severity of infection and the patient's age antibiotics may be needed.
What is Otitis Media. Otitis media describes inflammation of the middle ear. If she presented to her doctor with any of ear pain, ear pressure, fever, muffled or decreased hearing, drainage from the ear, her doctor may have diagnosed her with acute otitis media (aom). Fluid in the middle ear can occur with ear pressure or clogged sensation as well as muffled or decreased hearing, or no symptoms. (see comment).