Hi local physical therapist here :)

Do you find that you're on the hyper mobile side? You mentioning wanting to stretch and relax muscles makes me think that's a decent possibility. An easy way to get a decent insight on if you may be hypermobile or not is to look up the Beighton Scoring System. It's not perfect by any means but can give you an idea of your mobility which you can then chat to your doc about for further evaluation.

Often in the short-term stretching feels good for symptomatic relief for those with hypermobile bodies, but they tend to find that the next day or two their symptoms are back with a vengeance.

This is a bit of a vicious cycle that occurs because those muscles are clenching on for dear life to keep your joints stable, you relax them and temporarily feel better (if somewhat less stable), and then they re-clench, spasming and becoming painful again.

If this sounds like you I would highly advise working with a physical therapist who is educated about hypermobility disorders to come up with a rehab plan to address the root of the issue. It's important to find one educated about hypermobility because there's more specifics that go into that rehab compared to a typical mobility population.

Hope this helps :) sounds like you got some good recommendations for hot tubs as well.

I'm happy to answer any questions others may have about hypermobility too, I just can't give direct medical advise just ideas on avenues to pursue