A few months ago I went through weeks of intense burning in the muscles on either side of my spine in my upper back. This was followed by a couple of weeks pain. I was under a lot of stress. Every day my butt and legs burn where I sit. Now some mornings when I get up, my legs and arms feel weak and heavy. This heaviness goes away late in the day. Now my bladder is starting to act up. Could this be MS or CFS or stress?