Is It To Be Concerned About Abnormal Periods?

My 14 year old daughter started her mesntral cycle when she was 10. It has been pretty a pretty average cycle every month until this now. Her period has been going on for 2 1/2 weeks now, and has been pretty heavy the entire time. She has never seen an OBGYN - only her pediatrician. Should I wait this cycle out and see what happens next month? If I shoudl take her to a doctor - should I take her to the pediatrician or should I make her an appointment with my OBGYN?