Suggest Treatment For Abnormal Heavy Periods

My daughter is 13 years old, 4 6 ( I think?) and weighs 95 lbs. She started her period in February of this year and her periods were very light and lasted only a couple of days. This month it has been very heavy and as of today has lasted 8 days. She thought she was stopping but completely soaked through her underwear today which is day 8. Is this normal or should I take her to her pediatrician? I am 41 and continue to have heavy periods that last at least a week.