Hi M.,
As a massage therapist, I'd like to recommend baby massage to you to assist your baby in his growth. I, too, think this will resolve over time, however, if you and your husband massage your baby daily, several times a day even, I think you will find this encourages his body's muscles and bones to develop appropriately. I would concentrate on his neck muscles and back muscles with long sweeping strokes. Avoid direct pressure on the spine/backbones. Apply a massage cream or oil first, of course. Work not so gently that he doesn't feel it or it puts him to sleep. You want it to be effective. You could take him to a baby massage therapist, watch how she works and then copy her techniques on your own. Or google it. ;)
Good luck to you.
"Grams"
from the Pocono Mts. of PA