Suggest Treatment For Sprained Neck

Hi, I have a strained (may be sprained) neck. I was playing with my kid - about 15 kgs in weight. I lifted him many times raising him high...the game seems to have done it. It's been a week I can feel the pain at the base of the neck, moving behind the shoulders and going till the elbow on one side. Each morning when I wake up - its quite painful. I'm unable to turn my head around easily - thats painful too. Otherwise, I am quite active physically - regular at workouts.