I had this issue with my baby girl she only poops every 2 days I took her in and her doctor told me to only worry if she goes over 5 days ... but I just gave her plain water in her bottle and that seems to work
u can give him/her 2oz of water mix with 2 small spoons of prune desert, or u can grab a quitip put a bunch of bb oil to it put his legs on his stomach and put it in his behind and slowly move it in circular motion and make he's/her knees massage the stomach and watch out bcz the first stool is going to be hard but the rest can be so soft that it will come out flying to u so recommend to don't put ur face close 2 the bb but and have some one holding the diaper in a way that will protect you from getting poop on u
Make sure you're drinking enough water. You can also try massaging the tummy...you can Google on how to do it. Call your doc tomorrow and see if they suggest anything. It's possible that he/she is backed up from going from formula to breast...