Incontinence issues

So, I feel deeply embarrassed to even talk about this but my 10 year old (5th grade) sister has had in the past few years a problem in which she often ends up at the end of the day, when my mom helps her wash her butt, with some poop in her underwear, sometimes fresh sometimes clearly having been there all day. The girl is otherwise completely normal intellectually and physically, a bit emotionally unstable (cries for anything, can't be left alone with our 16 yo brother because they will fight physically, really prickly and sensitive about people looking at her the wrong way) and undisciplined. My mother blames the issue on her eating too much chocolate and recently, since the problem worsened during quarantine, on her being too focused on her videogames to realize when it's time to poop. None of these seems a plausible reason in a preteen to me, but she hasn't even thought of calling a pediatrician and sees is a discipline problem, telling my sister to 'solve it quickly'. This seems strange to me because my mom is normally extremely precise and hygiene/appearance focused and I can't find a reason why she'd ignore it so much. My sister generally says, when asked for explanation, that she didn't realize and acts like it's a surprise when she sees her undies are dirty, and often says she never pooped during the day so it's not even clear if the issue is incontinence or not cleaning herself up properly.I'm really scared about this, and not allowed to question my parents' parenting as I'm 21, don't have my own kids and only live here part time. I know stuff like this can be sign of abuse or psychological problems too and I'm really worried. Has anyone had experience with this? Not as medical advice, just to have a direction on where the issue might be via /r/Parenting https://ift.tt/2KgrOO7