Mine came on suddenly also during a long run on a Saturday. My legs just locked up and wouldn't move the right way. That night I had crazy pain my legs. I thought it was over training. This March, a full year after onset and 4 doctors later, I finally had a skin punch biopsy. The diagnosis was a relief, as one of the doctors told me it was all in my head and another one told me it was MS---no clinical evidence to support this. My current neuro has encouraged me to get back to running. It has been a slow and painful process. For the first month, it felt like I was running with tree trunks for legs and glass inside of my feet. I could barely make it a mile of jog/walking. However it seems to be paying off. My blood pressure is back to normal. I don't feel like I'm going to pass out all of the time. My legs feel pretty good unless I'm sitting or trying to sleep.

I'm sorry that you are experiencing this. I am grateful that my pain is bearable. I have had periods of pretty intense pain. I cannot imagine having it all of the time. I realize that it could be much, much worse. I'm also thankful to have found a place where I can ask questions. I try not to talk about this much in front of my friends. They just don't get it. When I first started back running, I had mentioned to a fellow runner how awful it felt with dead legs. She said, "We all have bad runs." I learned quickly to just shut it.