I had that, too, on my right leg. Having ripped up my left achilles, I knew what it felt like. This was not the sharp fire that comes from a torn tendon but it was painful and felt like it might tear. Also I had swelling on both feet. Now it is somewhat better, swelling gone, but my right leg is still stiff. I am aware that PMR is symmetrical...but since so little is really known about it, I don't take that as gospel.