Could bad gut health behind all of these bathroom issues for my kiddo?

For the past couple of weeks, my daughter(7) has been doing everything she can to avoid going to the bathroom. She'll cross her legs, say she doesn't have to go, then a little while later complain that her tummy hurts or that she can't finish when she does try. Nothing major has changed at home, she's drinking water and she's her usual happy self otherwise. We've been trying to get more healthier foods into her diet because I'm starting to wonder if her gut health is playing a role but other than drinking water, every meal feels like a battle these days.  We already have a pediatrician appointment in a couple of days but I figured I'd ask here too since I'm sure other parents have been through this. Did you ever find out what was causing it and what ended up helping?