hi i'd go for a second opinion, my 16yr daughter was born with Hirshsprungs, diagnosed when she was 3weeks old.. cronic constipation is the first signs, but this can happen at any age depending on how much of thebowel is affected.. it might be worth asking for hirshsprungs to be ruled out..
Go for a second opinion. don't necessarily need to get a new doctor, but for this problem, I would go for a second opinion to see what that pediatrician thinks. good luck.
If I was you I would be looking for a new dr.My son suffered from constipation since he was 6 months old.We tried all the home remedies and ended up at a GI dr when he was a year old.He just turned 4 now and they are doing a bunch of procedures on him to see if his rectal muscles are functioning normally and also doing a biopsy to check for Hirshsprungs Disease.(spelling).Not to say that you daughter has that but I would definitely not wait.My son has suffered almost all his life and it si very sad to watch him.when he doesn't have a bowel movement his whole personality does change and he gets really moody.I totally understand that she wont sleep or nurse on you.It really does effect their whole lives.I hope this helps you.I read about too many little ones that have suffered.