Ear-popping pain is one of the hazards of flying. For some, especially kids or those with colds, it can be quite severe. Mun Fitness Blog suggests several tips for preventing this condition, including the "Valsalva manoeuvre."
In the Valsalva manoeuvre, you close your mouth and pinch your nose shut and exhale forcibly through your nostrils. You'll hear a "popping" sound and the pressure should be equalised in your ears. (Unequal pressure in your ears when the plane takes off or lands is the main cause of plane ear.)
Besides several other suggestions for preventing ear pain when flying, Mun Fitness Blog also offers a great tip for preventing ear pain that happens when driving:
Ear pain also happens while sitting in a car which come down from a steep mountain quickly with the window rolled up. Leave a crack in the window when descending or climbing a steep mountain will help.
I've always just chewed gum when flying. What's your strategy?
How to prevent pain in the ear when you are in the plane? [Mun Fitness Blog]