Hello Doctor. My one and half year old son slipped on a wet floor and hit his back of the head on the floor. He cried a little and committed a bit but then was fine all day . Played normally and was energetic as normal. In the night , he vommited again and and had fever . He has running nose too. Since morning, he has not been eating or drinking much , and has been very low . Has fever too but does not let us check his temperature . Is this a sign of concussion or he has cold? Can the symptoms of concussion appear 12 hours after the injury. Please suggest