Hi djmarsat, it sounds to me like your eustachian tubes might be blocked. They are the thin tubes from the back of the throat to the middle ear. When this happens the middle ear is blocked off and the oxygen in the middle ear is gradually depleted causing an imbalance in pressure either side of the eardrum. This causes the eardrum to stiffen and become less effective, in turn leading to a dull sensation of hearing. It's a bit like when you go on holiday and your hearing goes dull as the airplane rises in the sky, you swallow or yawn, this opens the eustachian tubes and air pressure equalises either side of the eardrum, your ears 'pop'.
If the tubes are full of mucous due to the cold they will take some shifting, why not try to decongest with the old head in a towel over a bowl of boiling water, maybe a bit of menthol or something to loosen the mucous in your tubes, it might just work.
Shame you have to wait so long to see the nurse....
I wouldn't recommend hearing aids in this instance.