Thank you for your query.
is a constant process and not necessarigly a cause for frequency of motion. At this age children tend to put all things in their mouth. All things need not be clean and this causes frequency of motion which is causing the sore bums and presence of undigested food in the stools. I would suggest that you get your granddaughter's stool examined and, if required, give medicines accordingly.
A regular weight record will tell you if your granddaughter is losing weight or progessing fine.
I hope I have answered your query to your satisfaction. Feel free to revert back with any clarifications if you require.
Wishing your granddaughter all the best...