I had similar issues early in 2005. I was almost in a wheelchair with pain that came on within a six month period. I could hardly put one foot in front of another. All of my tests was normal. I was working as a Director of Medical Records, and I was sitting down with our Pathologist discussing my health. He reviewed all of my tests. He suggested that I might have Hypothyroidism. He said that lab values are usual values, but some people fall out of the lab norms. I was started on 25mcg of Synthroid, and within three months I was back to normal.
I was also told that I have an Auto-immune Thyroid condition. I had been off of Thyroid for 10 years, but had to go back on a low dose. My prescription is always changing. I presently take 12.5mcg 3 times a week. This is just my story as to what has happened to me in the past.
Good luck. I hope you can find out what is wrong with you, so you can get well.