For sure it isn't Guillan Barre--my cousin came down with it last year and the pain was horrific and it does start in the legs. He's starting to move again and uses a wheelchair but it might take another year to walk fully by himself. The only other thing I can think of is maybe M.S., the symptoms vary so much from person to person it's hard to tell. For yours and his sake I hope it's something more benign.