my 15 month old son was sitting on a barstool earlier this evening and fell off, landing on the floor and hitting his head, I think. I say that because we can't find a bump or swelling. He cried for a while, but later on seemed OK. He didn't close his eyes or stop breathing or anything. It has now been 2 hours or so, and he has fallen asleep. I am checking on him every little bit, I am just worried because I thought I've heard somewhere that if someone has a head injury you are supposed to keep them awake. I need some advice, please.