I have the same problem - my doctor says it is a faulty eustachian (sp?) tube. He said that Guifanesen (sp?), the main ingeredient in Mucinex sometimes works to relieve the pressure build-up. I get the "extra-strength" Mucinex, and take one every 12 hours, and it does seem to relieve the pressure.
As far as the ringing, he said the only thing he had heard of was "Quietus", which I hear advertised occasionaly on the radio. Due to it's high price, I've never tried it. However, there is a fairly new product at Walgreen's (and other pharmacies) called "Ring Relief." Compared to Quietus, it's fairly cheap. (about $12.00 for 60 pills here in AZ). For me it does not TOTALLY get rid of the ringing, but it does seem to take the edge off of it - make it not so noticeable.
Hope these give you some more ideas - I know how frustrating it is. Why oh Why didn't I use hearing protection when I was younger . . . ?