I suspect she went on Yaz as a cure for PMDD, but if it didn't seem to help, then it's unlikely related to hormones.
She could one of two things - she could see a psychologist or counselor who could help her to figure out why she has these break downs, or see a psychiatrist who will prescribe medication to calm her down.
My suggestion is to start with the counselor- because it sounds like it's more of an emotional issue than a brain chemistry issue (which would require meds).
This is exactly the sort of thing counseling is designed to help with - we talk with epople and find out what triggers such dramatic behavior and proviode them with better coping skills instead of breaking down.
I hope this helps, but please feel free to write back with any follow up questions.