To keep air pressure equal on both sides of the eardrum, a thin tube called the Eustachian tube connects the inside cavity of the ear to the back of the throat. Pressure inside the ear can build up if the Eustachian tube that keeps ear pressure in balance becomes blocked.
The Eustachian tube can become blocked in the setting of a cold or allergy, especially when nasal congestion is present. Poor function of the Eustachian tube also can occur with sudden changes in air pressure such as scuba diving and airplane landings.
Is your nose congested?