"...did some repetitive deco dives, had some joint pain / throbbing (started with elbow shortly after dive - then subsided for a bit), felt a unsteady on my feet... Next day aches seem to worsen slightly (still mild, but now in more parts of the body). Dull aches that seemed transitory and intermittent. Throb in the elbow for a few minutes, then gone. Dull ache in the lower back for a bit, then gone. A quick throb in the knee. Achy knuckles for a few minutes, then gone etc."30's, pretty fit, lift weights 4 x weekly. Probably should have included some of that in my initial post.
The whole experience was odd, and ultimately I'm no expert in hyperbaric medicine so will defer to those who are, but yeah, just a weird thing.
I'm "only" 56, but this all sounds exactly normal after some hard physical activity (and a boat ride for the unsteadyness).
Enjoy your time while it's still worth remarking on.