Jeepers. I wish I could think of SOMETHING. But it sounds like you've covered everything.

When I was a child, my legs would hurt so badly that I couldn't walk at times. They X-rayed me, tested for all sorts of things, and found nothing.
Then as an adult, I had more X-rays done, and they found I was born with an extra vertabra ~ an L6 !! Why couldn't they find that as a kid??? DUH!!

Makes me wonder if they haven't missed something on YOUR X-rays or MRI. Recently on an MRI they missed seeing scar tissue ~ and it was important that they SEE it for my doc to treat me!! You don't always get a "Good" radiologist. Sometimes they're real dopes!

God bless, and I hope you find out somehow what's wrong! Hugs, Lee