Can't poop

Hi. Ask lang bakit po may times na 3-4 days di makapoops si LO? She's 8 months old. Breastfed, cerelac, marie and water po kinakain/inom nya. And what to do pag nangyayari to? Worried na po kasi ako dahil hindi lang once or twice nangyayari to :( pls help. Need ko na ba sya dalhin sa pedia or should I give her more water? Minamassage ko din naman sya :( im afraid din to use suppository kasi baka masaktan :(