Here's a write up about it http://forums.webmd.com/.eec0d1d
This is not as uncommon as you think....You may have Exercise-Induced ETD (Eustachian Tube Dysfunction)
Exercise increases blood supply to all parts of the body. Along with this increased proliferation of blood, comes tissue engorgement...this is why your skin becomes red or flushed. When the tissue engorgement is around your eustachian tubes -- those tiny ventilation tubes that run from your middle ear space (the area on the other side of your eardrum) to the back of your throat -- it may cause the tubes to temporarily malfunction.
If the eustachian tubes clog, your ears may feel full and stuffy, your hearing could be a bit muffled, like they need to "pop". If the e-tubes lock in the "open" position (they are normally closed and only open briefly when we swallow), you may hear your own voice or an echo.
As long as this exercise-induced eustachian tube dysfunction resolves after you cool down, there may be no need to be concerned.
Since you are having other issues involving your ears, there may be other things going on, too...so, please keep working with the ENT until this mystery is solved.
(From the Ear, Nose & Throat: Rod Moser, PA, PhD)