I slipped on the ice around 7
Yes.  you're referring to an epidural hematoma where the person is hit in the head, goes unconscious, wakes up, and then falls asleep not to wake up again. This really only happens with a fracture of the temporal bone over the ear because there is an artery called the middle meningeal artery which ruptures and causes the problems.  This is not your case. Get some rest. If the headaches persist you might have had a concussion