Hello! 15 kHz Whistle in Both Ears, Caused by Cold Water (Waterskiing)

Just thought I'd drop in to say hi and see what news was about. My ENT has no advice (other than CBT) so it's down to me to keep my eyes out, so here I am.

Back at the turn of the millennium I was waterskiing in December, water temp about 5C, air temp about 10. After a dunking and brain freeze, I noticed tinnitus starting. It's a continuous super high frequency (or maybe multiple high frequencies) in both ears, slightly louder in the right. I do a lot of watersports, all year round, every year so this was unexpected.

ENT doesn't really recognise it as the standard hearing test in the UK NHS stops at around 8-10 kHz according to the results I got (printout of results).

I have historically had variable high frequency hearing reduction, meaning my right ear sometimes doesn't pick up things like the really high frequency parts of the sound of rain falling or shower sound, this creates an asymmetric sense which drove me a bit bonkers.

In investigating the hearing reduction the ENT highlighted an addiction to nasal decongestants and associated rhinitis causes by it. After a year away from the nasal decongestants, and on steroidal replacement, my tinnitus and hearing loss were both fixed (hearing rated as "significantly better than average for age" and tinnitus not gone but barely audible. Yay.

Things to note, Ibuprofen (even one dose) drives the tinnitus wild.
I've had a couple of sound based traumas (an engine exploding a foot from my head, for example) since then which created temporary increases in tinnitus but they always abated.

Then disaster last month, a cold water scuba dive kicked off the tinnitus all over again. No hearing loss associated but the tinnitus is pretty loud - currently affecting hearing speech a little. I'm not sure if it is pressure or cold induced, but I suspect cold again.