is it possible that hours later you could have rapid heartbeat. my son got hit in the head today at ball practice that is the only thing he's done today and then about 2 hrs ago we were laying down watching tv and he told me his heart was beating really fast so i put my hand on his chest and it was beating really fast and pounding out of his chest then bout a half hr ago he told me he thought it was worse it didn't feel worse to me but now im paranoid.