While travelling by air it is not uncommon for there to be rapid pressure changes. Normally in response to such pressure changes your ear equalises the pressure on both sides of the eardrum. The Eustachian Tube, which is the ear's balancing mechanism may at times have a problem or be unable to cope with the rate of change in the pressure, which could result in a earache or discomfort in ears and sinuses. The most significant changes in pressure generally occur during landing, takeoff or while passing through turbulence.
There are some remedies or simple measures that you can follow to avoid such problems or to remedy them. You can pinch your nostrils shut, suck in a mouthful of air and use your throat and cheek muscles to push the air to the back of your nose. When you have managed to equalise the pressure on both side you will hear a pop. If you do fall asleep in-flight make sure you are awake before landing. When you are asleep you don't swallow much and your ears won't be able to adjust to the pressure changes and may hurt. You can also try chewing gum, candy or yawning to relieve the pain. The pain dissipates as soon as the throat muscles are worked.
answered by G M