When did it start?
Was she treated by oral Antibiotics or any other medications before she got it.
Was she swimming in a public swimming pool?
Was she using a public toilet?
Is there a possibility that she was sexually abused? STD?
Do not expect her to tell you this. Shame associated with sexual abuse is so strong, many people would rather die than talk openly about it.
Sexual abuse is a common cause of suicide between kids.
Even the strongest people avoid talking about it. Just an example: Mike Tyson was sexually abused as a child, 40 years ago. It took him 40 years, tons of anger and hundreds of knockouts to talk openly about it.
It sounds like vaginal yeast infection.
Try vitamin A-cream. Works for majority with vaginal yeast infection.
She should avoid Sugar in any form. Vaginal yeast infection more often strikes those who's intestinal microbiota is already weaken by Antibiotics , sugar, junk food, steroids, vinegar, juices, sodas, icecreams, food preservatives , etc.
P.S. A child does not need to be sexually abused to develop vaginal yeast infection.
Sugar, poor immunity and a touch with dirty hands are more than enough.
Vaginal yeast infection is more likely to occur after a treatment with Antibiotics , or after washing with antibacterial soap, or after using soap with wrong PH.
Washing with yogurt may help eradicate yeast. Home made yogurt is better than pasteurised yogurt.