We had the same issues with our daughter. I noticed the back of her head on the right side (the side she favored when sleeping) had more of a flattened curve than the left side. We showed it to our pediatrician, and he said she had Plagiocephaly. He referred us to a therapy clinic that specializes in the treatment of Plagiocephaly called Cranial Technologies. They made a molded head band for her to wear, which has a foam inner layer that they shaved away every couple of weeks as her head grew and the skull plates realigned. They also taught us stretching exercises to do with her several times a day to eliminate the neck muscle tightness and head tilt. She did outgrow her first head band before her correction was complete, so we had to have a second one made. I believe it took six months total treatment time.
The younger you start, the easier it is (and the shorter time required for treatment) as the skull sutures are still soft and more pliable. You'll probably have a fight on your hands to get your insurance company to pay for it. They like to claim that it is a "cosmetic" procedure for appearances only versus being a medical necessity. The fact is that uncorrected the condition can lead to ear and vision problems, jaw / bite / chewing / TMJ problems, sinus problems, etc. Many insurance companies will deny paying it at first, and through appeals (including with the state insurance commission), MAY later pay for it. We didn't have any success, and ended up paying for it out of pocket. The fees for everything including all office visits came to $3,000 per head band. They offered a prepaid discount of 10% off if we paid up front, which we took advantage of.
She is three months shy of four years old now. To look at her today, you'd never know that her head was ever anything but the shape it is today. She has had no health problems related to Plagiocephaly. Believe it or not, she just had her first and only ear infection three weeks ago. It was expensive at the time, but if I had to do it again I wouldn't hesitate a moment to treat the condition in the same manner.
Google Pagiocephaly when you have time. There's a lot of information and personal stories out there on the web about it. Talk to your pediatrician, and look to see if you yourself can observe a mis-shaped area on the head. My pediatrician missed it in our first office visits, but when I pointed it out to him (I believe at the eight week visit), and we talked about the sleeping issues / head tilt / tight neck muscles, etc., he concurred that it was a problem, observed the incorrect shape, and wrote us a referral. I believe she was about twelve weeks old by the time her head band came in from Arizona and we started using it.
Best of luck to you. I hope this helps. God bless your family.