My son was 6 weeks when I took him to the childhood nurse and I voiced my concern to her over the same thing...she refered me to the public hospital physio department.
My son would follow me with his head to the right but when I walked past him to the left he would only use his eyes. He found it hard to turn his head to the left and would whinge a little.
Here is some info on torticollis which is what my boy had....and it sounds like your bub might have too but can easily be fixed.....
About 1 in 200 babies have torticollis, a shortening of a muscle in the neck causing their head to tilt to one side. The muscle affected is called the sterno-cleido-mastoid muscle (SCM), and it goes from the sternum (breast bone) to the skull just behind the ear. 'Torticollis' means twisted neck, and 'congenital' means that it is present at birth.
What does it look like?
Usually torticollis is picked up several weeks after birth when it is noticed that the baby's head is usually turned to one side, and it is difficult to turn his head to the other side.
The baby's head is usually tilted so that he will look up as well as to the side This tilt is due to the shortened muscle on the opposite side of the neck.
The muscle feels tight, and there can be a small swelling in the middle of the muscle, rather like an olive.
Causes of torticollis
Most commonly the muscle on one side of the neck is shorter than the one on the other side because the baby's head was held in a twisted position in the womb before birth.
For some babies, there may have been an injury to the muscle during birth. As the injury heals, scar tissue develops which makes the muscle tighter.
A baby can develop muscle shortenening if the head is turned to the same side most of the time, eg. for sleeping. This is not a congenital torticollis, but treatment is the same.
Treatment of torticollis
An examination of the baby's neck will usually be enough to be sure that the twisting is due to a tight muscle. X-rays or other tests are not usually needed.
The tight muscle needs to be stretched.
The muscle is passively (and gently) stretched by turning the baby's head so that the chin is moved towards the affected side. 'Passive' means that the stretching is done by a parent or someone else, not the baby. A physiotherapist or your doctor will be able to show you how to do this.
The baby can also be encouraged to stretch her muscle (active stretching) by putting things that she will be interested in looking at on her unaffected side.
Usually there will be improvement within 2 to 3 months and the baby will be able to move her neck fully in less than 12 months. Rarely surgery is needed to lengthen the muscle.
Problems from torticollis
If the muscle is not stretched, the muscle can become permanently tight.
Because the head is always held to one side, the baby's face can become asymmetrical and the skull can become flattened on one side (plagiocephaly). When the muscle becomes longer and the baby is able to turn his head from side to side, his head and face usually become a more normal shape. See the topic 'Misshapen head'.
Check out this website if you like more info...
Luke & ~Rhiarna~ 13.05.04 & Ryan 26.03.07