Well Im not a dietitian or a doctor, but iron is incredibly vital to soft tissue function, as are b vitamins. If you are deficient in these, it could possibly add to the pain of tendinitis. That likely explains the overall body pain. The lack of oxygen in the muscles due to anemia is probably amplifying the pain. I think the pain is likely a perfect storm of all your other issues combined.
Thank you for your response. I have a herniated disk that I've had for a long time. They did x Ray on one arm and one hip. It showed tendinitis. I asked if they would do a ct or MRI they said it was too expensive to do a whole body scan. I am iron deficient anemic and b12 and folate anemia. My labs look fine with the supplements. My Ana was positive but the titer was low so they said it wasn't autoimmune related. They just suggested physical therapy for my whole body. This is very painful. I went for 4 weeks.
Have you been checked for fibromyalgia? I have a friend with the condition and she experiences very similar symptoms from time to time.
If you have been checked and it is negative, and the many specialists and doctors you have spoken to say that it is nothing, I wouldn't worry. Assuming they did testing of course, blood, scans, and urine tests. If you're not losing weight rapidly for no reason and not showing any abnormalities on any blood chemistry or scans of any kind (CT, MRI, etc.) then it could be nervous system related or psychological.
I hope you're ok. I'm no doctor, so this is just layman advice and conjecture.