Before I ask my question I need to give you a little history. i had my left knee replaced in 2002 and it took 10 years before I could actually I was pain free. I had my right knee replaced in 2010 I m having so much pain that I m not sleeping at night. It is so stiff I can barely stand after setting. When I retired from work in 2005 I had 6 bulging discs. I rested and got my back under control. Now a new problem is happening and I ve been to see the doc that did my last knee replacement and he suggested therapy. I went to therapy but it hasn t helped. The problem is I m waking up during the night, when I do sleep, and I cannot move my right leg. It seems like my groin area has a catch in it and it is locked up and I can scream from pain trying to move my leg. Also, I m having a lot of cramps in my legs and feet. My potassium level is good. What is causing this new problem?