I HEAR its not unusual for breastfeeding babies to go a few days without pooping because there body just absorb the nutrients easier, leaving little to nothing left. As long as there still peeing like crazy, there shouldnt be cause for concern. However, My 2 week old had constipation a day ago and I read online to try a little warm water before feedings, and she got it all out of her system 15 minutes later. dont know if this will work for you :/ someone else online suggested that special baby juice you can buy at the store with some warm water. And if its hard poop then a Qtip with some Vaseline would help. Im not dr and I havent tried any of these personally so I cant say for certain if it would work for your case. Good luck!