Ear problems - NOT an infection or water in the ear!

For the past 4 days, my ears feel like I'm in an airplane - all plugged up. If I pinch my nose and blow, they clear out but only for a couple minutes before sealing up again. Pretty much just like on a plane. My doctor told me today (after determing there is no infection) that swimmers are prone to problems with the eustachian tubes and that there's not much that can be done about it. He suggested wearing ear plugs while swimming, though I'm skeptical that is going to help. Anybody else have experience with this problem? It's REALLY annoying. I never get ear infections (not since I was about 10, anyway) and I use Swim-Ear always after swimming to dry out my ears. It really seems to have nothing to do with water in the ears, just this sudden inability to balance the pressure.