Nak, if baby's poop pattern changed na and sobrang tagal ng 2 days na walang bowel movement, please check with baby's doctor or pediatrician agad, mas safe na, especially kung may other signs din na unusual. Constipation in babies can sometimes need professional guidance, at better safe than sorry talaga!
One of my mum friends' baby had similar concerns and the pedia was able to check right away, so don't hesitate to call or visit. Sending you and baby lots of love!