Middle ear infection
A middle ear infection often originates from a cold or other respiratory problem. The infection moves to one or both ears through the eustachian tubes. These tubes regulate air pressure inside your ear. They connect to the back of your nose and throat.
An infection can irritate the eustachian tubes and cause them to swell. Swelling can prevent them from draining properly. When fluid inside these tubes can’t drain, it builds up against your eardrum.
Outer ear infection
An outer ear infection is sometimes called swimmer’s ear. That’s because it often starts as a result of water that remains in your ear after swimming or bathing. The moisture becomes a breeding ground for bacteria. If your outer ear is scratched or if you irritate the outer lining of your ear by putting your fingers or other objects in your ear, a bacterial infection can occur.