Hi, thanks for using healthcare magic
Children can experience thrush
which can be itchy and uncomfortable as in an adult.
The cream can be used but you must be careful to apply it to the external aspects of the genitalia, just beyond the labia.
It is not to be inserted as it would be in an adult female.
The cream will not harm her.
You may want to consider using some sitz baths to help her with the soreness.
I hope this helps