during potty training for our oldest (girl) she got one and so did our friends daughter a couple times from not wiping the correct way. The joys of girlhood.
In the same vein as what Amy is saying about good bacteria...because CFer's use antibiotics more frequently, they have an increased change of developing yeast overgrowth in the intestines and UT. This imbalance can lead to digestive upset, UTI and a miraid of other issues if it goes on. Often this can be the underlying issue. Daily probiotics (acidophilius) is a must for all CFer's in my opinion. There are tons of great chewables on the marker KidDouphilus is one of them. This might really help balance things out.
Keeping sugar and breads to a minimum are also critical to maintain a good digestive tract.
Best Wishes,
Jody