My son had this problem and he was crying alot due to this lack of bowel movement. My mother told me an old wives tale of ONE teaspoon of brown sugar in 4-5oz of water. At first i was sceptic to this, so i went to the doctor for a second opinion and she advised the same. She told me that some old methods worked. So i put ONE TEASPOON of brown sugar in 4-5oz of water in a bottle and let him have about 1-2oz of this for 2 days maximum and he started to have bowel movements pretty much straight away. I've advised other recent mothers of this method and all have informed me that this works.
If you choose to use this method, only use one teaspoon to 4-5oz of water and ONLY let them drink 1-2oz of this as too much isn't good and your'll probably end up with the other end of the scale. Diarrhoea. ONlY give for 2 days maximum.
This has worked wonders with myself and many of my friends who have become recent mothers and is a natural and harmless method.
Hope this could be of some help to you.