T.H.
My niece had a issue with this as well. Take her to a dermatologist. I cannot for the life of me remember what her condition was called...something scorosis or something. Sorry I'm drawing a blank! Anyway there was a solution. It is a lifelong issue so she'll need to use the prescribed cream unless they find another way to fix it. It is technically a consistent yeast infection type issue. I do know that her dermatologist said that if untreated for extended periods of time it can cause vaginal damage. I am in no way saying this is what your daughter has, but a dermatologist or Gyno may have a better take on it.