FWIW, I have to take a hearing test every year for work. A few years back I was in the booth doing the test and everything was going fine. The machine tests one ear at a time, and the first ear took a while, as usual. When it switched to my other ear, the test was over pretty quick, but I still heard all of the tones, or so I thought. The nurse opened the door and said she need to check my ears, because something was wrong. She looked in my ear and said there was... [DISCLAIMER: may be gross to some!]... some wax build-up in my ear. I didn't even notice I couldn't hear the higher pitched sounds. Anyway, she told me to go to the Pharmacy and get some ear wax removal stuff. It was only a few bucks, and 24 hours after using it, the build-up was gone and I had my hearing back. You might want to try some, since it sounds like the same thing that happened to me. Its a liquid and you put a couple of drops in your ear before bed, and a cotton ball to keep it in.
Roger