When DS fell off a chair and hit his head on the tiles Health Direct (WA) told me to put a cold flannel on it and to watch out for a temp, stumbling when he walks and if his pupils in his eyes are different sizes (indicates concussion) and if any of those occured to ring them back or take him to GP/hospital asap. Also, if he wants to sleep, let him but check him after one hour, wake him up to make sure he's still going ok.