Har, 3 points!
I have this same problem myself and it came out of left field. Surpringsingly it seems to affect only one ear.
I did the whole nine yards and nothing really worked. I wound up have hearing aids.
Wish I could be more positive but I know from personal experience. It affects all age groups. No one seems to know what causes it.
The only way to regain hearing in the affected ear would be a cochlear implant.