Okay. You have suffered a concussion. You turned around too quickly and the bass player's headstock caught you on the back of the head a little too hard. You were out for about an hour or so, but the doctors thought it best to keep you sedated for a bit and observe you. X-rays indicate nothing was broken and there will be little lasting damage, but you'll be groggy for a few days. Bit by bit, your memories from just before the hit will return. So don't sweat it. You'll be back to normal in no time at all. Until then, if you notice anything unusual, let the doctor know.