Struggle with 14-yo Daughter

My 14 year old daughter recently appeared to become incontitent. For about a week she would appear to have small spots of wetness, and then recently, while she was doing homework, she emptied a full bladder all over herself. This was repeated several times in the next week. Concerned, I talked to her, and took her to the doctor. She said she didn't realize she was going until she felt wetness. The doctor didn't find anything wrong, despite several tests and referrals .Anyway, she now wears a diaper, and seems perfectly happy. However, she refuses to change during the day at school or at home. I have talked to her about it, and she says she just doesn't care enough to change it. If left to her own devices, she would only change when she showers. I have checked that she can be discreet when changing at school.As a result of this, she often has an overfill diaper when she uses it again, meaning she comes home with wet pants. She doesn't really seem to care about this.What should I do? I am worried about her. Is it possible she is doing this on purpose?No trauma at home, or any changesEDIT: forgot to mention that stumped doctor talked to urologist. via /r/Parenting http://ift.tt/2nHfWsH