My 14 year old daughter having problems using the bathroom?

It took my child years until she was potty trained. She finally got it when she was 6. She has an overactive bladder. She used to wet the bed, but stopped when she was about 12. She recently started having accidents. When she has to go, she has to go. She says right when she gets the feeling she has to use the bathroom she can't holdit. She has to go right then. She started having accedents at night again. She wears diapers 24/7. She wears them to school and at home. She has pe this semester.there switching classes in 3 days and they are required to wear a pe uniform and I'm scared when she changes the girls will see her diaper.