Years ago my wife had similar shock like feelings in her scalp. They would last for just a short periods of time. Most doctors diagnosed this to be a mental condition. Fortunately after three months of doctoring a nutritionist diagnosed this as hypoglycemia which is a drastic swing in sugar levels in the body. Apparently this causes other organs to react abnormally and to release chemicals into the blood stream that caused the shock like feelings in the scalp. I'm not saying that your condition is a result of hypoglycemia but it may be due to a similar chemical reaction that is causing your symptoms. What my wife went through was very scary but fortunately the cure was simple.........a proper diet.