When I exert myself or get hot, I experience stabbing pain in my chest, difficulty breathing, and my nerves fire off in my shoulder, back, sciatica. I can also experience cramping, loss of some motor skills. This is a recent thing. I had a CT with die, and a chest X-ray, and nothing showed up. It s very scary, when it happens, and the onset takes me by surprise. I have a history of nerve problems, and I have had neck and lower back surgery, years ago.