I sympathize with your situation. It sounds very similar to chronic pain issues I've suffered for most of my life. I know how despondent it can make you feel, I've been there. Being able to enjoy physical activity is very important to one's mental and physical well being.

However, in recent years my condition improved dramatically. I believe I've an autoimmune disorder. Here's some suggestions that helped me figure it out and reverse it's progression:

Try high dose magnesium (Mg) for short while. 600-900mg of magnesium citrate daily is best I think. It's not to correct a deficiency. It's for the effect it has on the bowels. At a high does the bowels loosen and the microbiome quickly changes. This alters how new immune cells develop, hopefully positively as it did for me.

I wouldn't recommend taking Mg like this long term though. The best way to positively improve the balance of components of the microbiome is to consume a lot more fiber of various sorts and sources than is common in the western diet. The usual advice on diet is to be recommended. Cut down on highly processed simple carbohydrates. Some meat is ok but not a lot. Same for alcohol. If you want to eliminate meat that's ok as long as your diet is still varied and includes probiotic and fermented foods. And generally eat a lot more plants.

To sum up I believe the immune system is groomed in the gut and the microbiome is an essential part of that process. A malfunctioning and misdirected immune system is responsible for many illnesses from those well known like arthritis to ones we probably don't even have a name for yet.

Whether this helps you or not don't give up and keep looking with an open mind.