This happened today and does on occasion. I get light headed, tingly fingers and toes, breathe heavy, get warm, get weak, sit down, lie down, and then all of my muscles (whole body) stiffens similar to having a contraction, but all over. My hands clench into tight fists that no one can open, I can t talk because my tongue is immovable, my feet are pointed and stiff, everything starts to hurt from being flexed for so long. This lasts about 15 to 20 min and I slowly start regaining mobility. I do nothing but breathe deep and steady to make it go away. The EMT took my BP - normal, my blood sugar - normal, pulse - normal. No one can explain it.