Newborn baby HELP

Stephanie
So my daughter is 12 days old. (Waiting to hear back from my pediatrician, but sometimes y'all have experienced similar things so I don't see the harm in asking) - and yesterday she had two hefty poops. She is breastfed, and even though she has had several wet diapers all day, she has yet to have a poopy diaper today. I have also noticed since yesterday she stiffens her legs up a lot, and arches her back and fusses. She has not spit up once, so it appears she may be constipated or having a hard time passing gas? Has this happened to y'all? Any advice?