I have RA, I frequently have pain in my hips which I have just assummed is from the RA. Lately, I have had some low back pain, and pain in my thighs. Yesterday, I had severe weakness in my legs-they felt like jello-very shaky. It frightened me enough that I went to the ER. All of my blood work was fine and I was told to follow up with my PCP-but the weakness is still there. I am weak all over today. What could be causing this?