I been having this problem for years after I gave birth to my daughter... I was driving in my car and all of a sudden I got a sharp pain up my legs and knees it was so painful I almost crashed the car. My rhuematoid factor test was high. I went to a rhumatoligst and came up negative... I did have a MRI done which showed a bulging disk and facet arthritis of the spine... Lately I wake up very stiff in the morning hard for me to walk and also pain in my hands and fingers now...The doctors did x rays but could not figure out what was wrong with my legs and knees... I just started getting the pain in my hands and fingers very painful... The last time I went to the rhumatolist he just told me sometimes you get pains....