Not sure... I would need more info about the yellowy pieces.
I know that psyllium turns into a yellowish glue-like substance when it is combined with water. (Psyllium is the main ingredient in Colonix.)
Think of psyllium like this, have you seen those 'poop-ropes' you see people holding up on Colonix website? Well, the middle / core of those ropes are the yellowish psyllium 'glue'. This yellowish 'glue' then sticks to everything it can in the colon, thus cleansing it when you have a bowel movement. That's why you see feces stuck to those ropes.
I would guess that is what your daughter is seeing, but I would need more info about the yellow pieces.