8 year old daughter keeps washing her genitals with toilet sprayer for long time

[Parentingtips]

My 8 year old user the water pressure of toilet sprayer once a day or sometimes twice to clean her genitals.she doesn't rub or uses hand to clean the area but cobstantly presses tgat spray er fir 10 to 15 minutes inspite of our repeated scolding.She nevers gives an explanation on why she does it,on insisting she says to relivery from itching,sometimes says to get rid of slippery feeling.she refuses to show me if there is any readness or discharge.when she fell asleep,I checked her vagina and anus are clean.cant find anything.she started doing it when she was around 7 and sometime whrn there is pinworm issue she does it more often.She won't let me help her with cleaning,neitger allows me the show her how to clean properly instead of pressing the toiler sprayer for so long .until  we yell at her or force her to leave the sprayer,she doesn't care to listen and keeps using tgat sprayer.can anyone explain why this is happening ?how can I help her hid rid of such bad habit

[Jakerpies]

Why is this a bad habit? Why are you yelling at her? Why can't she continue with it? It probably feels good to her.

[Jakerpies]

Are you upset with her because she is wasting water or because she is in the bathroom for so long? Or is it just because she isn't obeying your order?

[Sandman2]

I would guess that she has found out that the spray feels good.  That is pretty normal.  Point being from many, many other posts on this forum....I doubt that this is a medical issue, but one of feeling good.  It is not a bad habit, but a normal one.   The standard reply is that this is something that you want to do in private...which she is doing.   If you can somehow stop her from using the sprayer, she probably will find other ways to feel good.  

But ya, 10 to 15 min. is a long time to hog the bathroom.   Outside of setting a timer, I have got no clue on what to do.  

Perhaps the book I recommended in your other question might help.  And you also might want to see if this one might be helpful.
           https://www.amazon.com/dp/164152166X/ref=sspa_dk_detail_1?psc=1