Hi Ritzyglitz, Welcome to Mystic Board
I found that diet is a big area that helps, strictly checking ingredients and keeping a diary of everything eaten and drunk, seeing which ones trigger the 'black moods'. Not easy with a 15 year old, and you will probably have tried this anyway but I found that all the usual additives and preservatives, colourings and flavourings really made things a lot worse. Then we noticed that there was a pattern a few hours after eating certain foods, perhaps a low blood sugar level , but we began to be able to pinpoint when outbursts would occur and limit them by giving a small safe snack. Gradually the bad times got fewer, there was still the anger and frustration and some days that would be hell. But slowly we all noticed a difference. I ended up taking course after course in order to find out all I could to help, and we realised that there were other factors like OCD and dyslexia and Aspergers, everyone was very quick to blame ADD or ADHD and bad parenting and food that they overlooked other possible causes.
You aren't alone, and it is hard to cope. But at 15 things are at their peak of hormonal chaos, it does get better, honest!