My dd (14) has started her periods recently. The first one was light, no fuss, no pain. The second one has been a nightmare. She had to come home from school, lots of pain, persistent nausea, loss of appetite, terrible diarrhoea, heavy heavy bleeding with big clots. She has soaked through pads in less than an hour. She had a day and a half off school and is now back but still dealing with heavy flow. My own periods have never been anything like as bad as that. We have figured out the right level of protection for her now, I think.
My instinct is that we should just ride it out and see what the next one is like - that her body is just sort of figuring out this change and there's no point going to the Dr right away. But maybe I'm wrong?