Your child has a concussion. Now what?

Your child is in the thick of the game, running her heart out in a race with an opponent to chase down the ball. Suddenly, that opponent throws an elbow, striking your daughter in the temple. Your daughter crumples to the field, lying motionless for what seems like an eternity. The referee stops play and you and her coach rush to her side. She appears dazed, but is alert and able to count the fingers held up by her coach. She walks to the sideline without assistance and you think all is well.