I am so sorry.

I do know how you feel.
Have you ever been tested for Lyme disease or have you any memory of ever being bitten by a tick? I was treated for Lyme back in 09/10 and the flu symptoms stick in my head. I was sick enough to die and wonder why I didn't. No joint pain but I did have nerve pain that was almost unbearable.
Whatever you have going on I hope the doctors can get to the bottom of it for you. Not knowing is half the battle.
Steroids have always helped me also. Tried to limit them to only 4 shots a year but I needed to quit that route. Steroids are just plain nasty as far as side effects. The Methotrexate isn't perfect for me. I am having side effects. Fatigue the day of my injection, loss of appetite and today I suddenly developed light sensitivity. Bright lights hurt my eyes. Unpleasant but as long as they don't worsen I think I can tough it out.