I have a similar question to one that was posted. I have abrupt/severe muscle spasms. They seem to happen only when I’m resting or am extremely tired. the problem is that they are not limited to any specific part of the body though the torso is the most common area. When they hit I get about a seconds warning. I feel a pressure in the back of my head just before the spasm hits. They are literally a jolt, the overall effect is like an electrical shock causing the feeling of an explosion in the back of my head as well as a muscle spasm.