Ear infection and eustachian tube dysfunction

The Eustachian tube functions by opening air flow into the middle ear. This air helps to expel the mucus keeping everything clear and everything vibrating in full range. It does this when we apply mechanical movements that force it open and closed. Things like yawning, swallowing, or chewing. Try it now, open your mouth wide like your yawning, you can feel the pressure as the tube opens just below your ears.

There Are Several Causes for Eustachian Tube Dysfunction
Many of the causes of Eustachian dysfunction are diseases. These can cause dysfunction for a few hours or weeks, and even permanent damage in some cases. The cause will often give you a clue into the duration. Some things that trigger eustachian tube dysfunction are:
Allergies: Allergies can cause mucus build up. This causes inflammation around and within the Eustachian tube. This includes allergic rhinitis, hay fever, or anything else that tends to also trigger the nose and congestion in the head.
Serous otitis media or Glue Ear: This term was coined around how the fluid that has filed in the middle ear is of a glue like consistency. This blocks the flow of fluids and can cause pressure, ringing, and pain.
Colds: Any infection to the throat, ears, nose and/or sinuses can inflame the condition due to how it causes mucus buildup. Thick mucus evolved from the infections can block your Eustachian tube. It can also inflame it causing swelling and following pressure. If this is the case treat the cold or infections first and the rest, including your hearing, should return to normal as the cold/infection heals.
Growths in the nasopharynx: enlargement of the adenoid tissue which normally is located in the nasopharynx can affect the opening and closing of the eustachian tube. If left untreated, it may result in the accumulation of fluid in the middle ear called serous otitis media and more long lasting hearing loss. Although uncommon, cancers of the nasopharynx are occasionally picked up because of ear clogging from obstruction of the eustachian tubes. This is a good reason why ENT specialists will take a peek inside your nose with a small camera called an endoscope.

When you feel a pressure in your ears such as when driving through mountains or changing elevations your Eustachian tubes tend to close due to the air pressure fluctuations. This is why you should perform the valsalva maneuver, which is when you pinch your nose shut with your fingers and blow (with your mouth closed) to “pop” your ears.
You are actually not popping your ears but rather opening the closed/blocked tubes. When they open, the pressure can cause them to overextend causing a temporary pain in the deep ear canal (middle ear).
The next time your ear “pops” when you go down an elevator or descend to JFK from your exotic vacation, you now have a better understanding of what is happening.