Pinworms and other ailments are very common in children, and cause irritation.
You can't go wrong by giving her a little gentle but effective parasite cleanse twice a year.
Read in the the Ask Humaworm forum until you understand the subject.
The little one doesn't need to hear anything about 'crawlies', just that this is what we do at our house...we take these little capsules...to be sure we are well.
If this should be the source of her interest, it would quickly fade, I would think.
Wish I'd have heard of this thirty years ago.
Now it is my task to pass on the info, cold turkey. Sigh.