That happened to me once as well, but it wasn't immediately after. I was knocked out going for a fumble in a youth football game (don't remember the hit or the play but remember waking up soon after). I came to, obviously went out of the game for good and probably 20, 30-ish minutes later I was throwing up. My parents took me to the hospital, I took some tests and was OK'd. But it can definitely be a serious thing. Hope he's alright. No sense in rushing back to make a 41-13 game a 34-13 game.