What are the reasons for prolonged menstrual period duration?

Patient's question:

Detailed medical condition and consultation purpose: Menstrual period is usually 10-15 days, want to ask what causes this
History of previous diagnosis and treatment, as well as effectiveness: Not diagnosed at a hospital

Doctor's answer:

??????Hello: Considering the syndrome of menstrual irregularity with deficiency of qi and blood: The menstrual cycle may be advanced or delayed, the amount of blood flow may increase or decrease, the duration of menstruation may be prolonged, the color may be pale, and the quality may be thin. Or there may be lower abdominal pain, or dizziness and blurred vision, or fatigue and weakness in limbs, or pale or sallow complexion, poor appetite and loose stools. The tongue is pale-red with a thin and weak pulse. Treatment should focus on replenishing both qi and blood. Medications that can be used include Bu Zhong Yi Qi Pills, Shi Quan Da Bu Pills, Wu Ji Bai Feng Pills, Ba Zhen Yi Mu Pills, Ba Bao Kun Shun Pills, Nu Jin Pills, Dang Guiiao Jing Pills, Dang Gui Hong Zao Granules, Gui Pi Pills, Si Wu He Ji, etc.