question: Hello. Several years ago, while rafting in a stream, I hit the back of my skull pretty hard on a large rock. I m quite sure that I had a concussion and was in pretty, bad shape for the rest of the day. Now, four or five years ago, from time to time, it causes me a fair amount of pain. Tonight, it hurts to the touch. Any idea what I might be dealing with and how concerned about this I should be? Thanks In Advance, Andrew Gray