K.U.
She needs an appointment with a gynecologist. I had a friend once who was prescribed birth control pills at 15 years old, just because her periods were so bad, and they really helped. Something like Pamprin that is over-the-counter might help with the pain and bloating, but won't do anything about the heavy bleeding. But it could also be something else entirely, so an exam with the doctor is what is in order.