My daughter was constipated a lot to the point I could tell she was in pain and I had to use ky jelly and a qtip to "stimulate" her butthole. I know it sounds weird but you just rub it don't really have to penetrate. When they are that young it's hard to give them anything and suppositories even for infants are painful. And if you get her cleaned out good and she backs up again find a specialist. My daughter ended up having a medical condition and needed surgery.
Thank you for your advice. I will try that. I'll speak to her pedatrician on Wednesday to make sure nothing is wrong.
It may be the formula. You may have to use the sensitive formula if you are formula feeding. Not sure if your breastfeeding...with my first daughter she got constipated alot and even when she grew older she had to drink soy milk and lactose free milk. Hope your baby feels better.