Torticollis can affect almost any child. It is caused by a tight muscle called the sternocleidomastoid. Often this can happen as a result of positioning in the womb or as a result of a child spending too much time in one position and developing plagiocephaly. There are other reasons but these are two common ones.
It is highly recommended that you see a doctor and/or a physical therapist to make sure there are no other underlying causes for the torticollis but often the way to help with its improvement involves stretching, strengthening and functional retraining (not as scary as it sounds).
For stretching you want to be really gentle. Whatever direction your child holds their head, you would want to gently stretch in the opposite direction. For example, if your child prefers to look to the left and tilt their head to the right you would gently try to bring their left ear towards their left shoulder while keeping their eyes looking straight up (i.e. their head is not turned to the left or right). You would also try to turn their head to right while keeping their body straight (don’t let their shoulders follow them). I’m sure you can imagine that kids may not enjoy this (although it is a little easier when they are tiny) so you may want to have something they enjoy looking at in the direction you are stretching them. You want to distract them from what you are doing.
I have also worked on strengthening by using a therapy ball. I love to use a therapy ball for tummy time (which is important to work on with you child). By using the ball you can move it so that your child has to use different muscles in their neck. Their head will automatically want to right itself in the middle (prolonged torticollis can affect this ability which is why you want them to get lots of exposure to different positions). So for the same example we were talking about above you would want to move the ball (while stabilizing your child on it) so that they have to lift their head to the left. You can also have something really engaging to the right so they will turn their head to look at it while they are on their belly. Don’t put it too far off to the right but just slightly so that they have success. In the beginning only have them practice moving their head in these directions. As they get stronger you can have them hold it for longer periods of time.
Functional retraining (my definition for this post) is to encourage your child to actively engage in looking and moving in the direction opposite of their torticollis. So, if you normally sit on one side of them or hold them on one specific side then hold them on your other side. If you have them sleep with their head at one end of their crib, switch it so they are lying at the other end. By changing their positioning they will have to use different muscles to look at things and not get ‘stuck’ in the same pattern.