Heavy cycle

My daughter has been having increasingly heavier cycle this month. Typically only 4 days long but is at a week for the first time. The length doesn’t raise the 🚩 but the fact that she changes her pad every 60-90 min. She’s only 15 and is regular. She has been feeling shaky and dizzy but the ER wasn’t very helpful. They didn’t even draw blood or check her physically. Just recommended birth control. So frustrating! Sorry for venting but worried about my big little girl(young lady)