Many of your symptoms resemble my symptoms of fibromyalgia. I was dxd with fibro just over 10 yrs ago and live in pain 24/7. sitting hurts, standing hurts, just as you said. Leaning on my wrist hurts, as you mentioned. I no longer sit on the floor because of all of the pain I will have in all of my joints. Positions that most people take for granted, like sitting, are painful and can cause a muscle spasm that will last weeks. Something hurts ALL the time. Joints are a big pain with the tendons & ligaments really hurting when and afer I exercise, especially the elbows, hips, wrists, knees & fingers. I have massive spasms in my shoulders, neck & lats on the back (around the shoulder blade, as you mentioned) and those areas are always tight & always painful. I sleep sitting up to reduce the spasms in those areas. On top of that I was recently dxd with MG. It would be nearly impossible to distinguish the 2 at this point, so I rely on my past with fibro to try to figure out what issue is which.

Good luck on your journey!!