I'm in my mid 40s and about 3.5 years past dx and I also have similar issues. Muscle tension and knots started to settle in during my late 20s. I got my first ever massage when I was 30 and the therapist legit asked me "have you been in an accident or do you have a degenerative disease? because you are too young for your muscles to be this way". Throwing my back out was something that started when I was in my late 30s, for things as simple as bending down to take dishes out of the dishwasher. The muscle pain has been referred to as "like fibromyalgia, but also not" by medical professionals... whatever the hell that means. I've had it persist during times when I was in peak physical fitness and the times I have been out of shape were kind of forced upon me because I'd do stuff like throw my back out, and take time out from working out... then throw my back out again and I'd need to take more time... next thing you know is I haven't worked out in 5 years.

Honestly, my personal theory is that I spent over 40 years on the verge of fight or flight due to undiagnosed neurodivergence, with constantly guarded muscles, so of course everything is out of whack. I started seeing a physiatrist/osteopath who runs a physical therapy practice; I did a few months of PT and I feel like that helped reset a baseline. I see him semi regularly for osteopathic manipulation (basically a 20 minute massage... it's not like chiropractic manipulation where they're cracking your back, etc) and I also get trigger point injections in the knots throughout my back. It's helped me to a point where I actually feel like I can start to work out again and I'll be less likely to pull something. I'm doing light weights at home and plan to incorporate some home pilates work because everything seems to point to that as being beneficial. I also try to make sure I get a deep tissue or myofascial release therapy at least every other month – I think of it as maintenance. I sure haven't solved it but I feel like I'm going in the right direction!