One diagnosis which most GP's and Most ENT's overlook is
Patulous Eustation Tube - The symptoms are very, very similiar to Otis Media/ Eu tube disorder- blocked tubes, dulled hearing, difficult to clear gunk etc. (This condition can sometimes be accompanied by acute tinnitinus) Unfortunately there is no foolproof cure at present but there's lots of research going on. The Eustation tube Institute in Geneva is one of two places which can possibly help. The other is in Boston, US.
It would be interesting to see what decompression does as it cannot blow the eardrum as the EU tube remains open with this disorder...