Doctor, I have a menstrual period that lasts more than 1 week, bleeding a lot, sometimes it drips a lot, sometimes it gets better but it doesn't stop, I feel normal in my body? Can you tell me what's wrong with me and how to treat it?

Hi doctor! Doctor, I have a question about my sister's puberty period. The first period appeared about 10 days, after 2 days, it came again, so far 8 days have not stopped. I'm so worried asking a doctor to help me get my period lasting 8 days in the first cycle, is it okay? thank you