I was diagnosed with PCOS when I was around 12/13. Having a supportive and understanding mother helped me get through it more than I can say, but other than that there's wasn't much other than plenty of painkillers, heating pads and rest that really helped, at least for me. My mother also let me stay home from school if I had a particularly bad period or flare up. I wish you both the best, your teen is stronger than they know <3