How old are you? Have you ever had any 'bendy' joints?
I ask because you describe the sort of widespread pain I have, and that many people experience as part of hypermobility syndrome. The syndrome is different from simple 'hypermobility', because (a) most people who are just 'bendy' don't have pain or other symptoms, and (b) some people who have the syndrome lose their bendiness over time. It might be worth checking the diagnostic criteria here .
HMS often goes undiagnosed for a long time. In my case, I only got diagnosed last year, in my late 40s, after several years of pain and other problems, and since then I have 'seized up' so I am hardly bendy any more, and am developing arthritis in several joints.
They don't seem to understand the stiffness of HMS very well. It seems to develop because our ligaments aren't supporting our joints properly, so our muscles have to work harder. Then, as we get older arthritis may add to the pain... Or if we get unfit, so that muscle tone is lost, muscles may go into long-term spasm to hold joints in place, which hurts a lot.
I don't know if this helps at all. I just thought it was worth mentioning because my own experience was that my HMS wasn't really considered until I actually became less bendy and more stiff.
Whatever it is, I hope you can get some help. I know how exhausting and difficult long term pain is.