I would ask your doctor. Are you brestfeeding? Or just formula?
Take a qtip and put it in Vaseline and then stick it in her butt a little bit. Just stimulate it a little and she should go. A warm bath also helps relax so she should poop
If you are not too far from giving birth try some breast milk. :)
I've heard mixing prune juice with water to dilute it...and when she strains, support her feet like they do mom's in labour...not sure what age the prune juice is OK for though...maybe call Dr to be safe.
Try doing bicycles with her legs, I would call the pediatrician since she is a newborn. I wouldnt give baby anything without doctor's approval.
what you're describing sounds like she is intolerant to something she's eating it doesn't sound like constipation at all it sounds like stomach cramps talk to your doctor about it