Try taking a deep breath of air. While pinching your nose and keeping your lips tight, blow strongly but steadily against your puffed cheeks. You should feel the pressure change in your ears . Continue blowing and your ears should be cleared.
You can also try swallowing repeatedly, chewing gum, or stretching your jaw by "yawning."
Try to take deep breaths and relax by keeping calm and massaging your muscles, especially the ones around your ears and neck.
Take a hot, steamy shower. The heat from the steam should ease the pressure in your ears and relax your muscles.
If your ears are still clogged, try taking an antihistamine, which should help relieve the pressure as well as help prevent clogged ears in the future.
I'm in my school's swim team and clogged ears are pretty normal to me. Also, my family travels a lot and my dad always suffers from clogged ears after a flight.