My 12 Years Old Daughter Had First Peiods Before 8

My 12 years old daughter had first peiods before 8 months, flow was very much, last for 8 days, then disappeared, now AFTER 8 months it started again, this time also flow is too much, changed 14 pads in last 18 hrs, consulted Dr. She suggested REGISTRON want to know how it works on body, please help and oblige