Hi,
When bleeding occurs for longer period than it is usually as in your case then  there are few possible causes and most common is a 
hormone imbalance. PCOS is one of the causes of 
hormonal imbalance. While some causes may be easy to treat, others can indicate a serious underlying condition. Whether you notice spotting or heavier bleeding in between periods, it’s important to see your doctor for testing, diagnosis, and treatment options.
Other potential causes of 
inter-menstrual bleeding include a growth in the uterus or cervix, stress, change in medications, 
miscarriage and 
vaginal dryness. Your doctor will also likely give you a physical exam, including a pelvic exam.
Diagnostic tests can help your doctor find the cause of the bleeding. Your doctor may draw blood to check hormone levels. Then right treatment can be recommended.
I hope I have answered you query. If you have any further questions you can contact us in every time. Wish you a good health.
Regards,
Dr. Ivan R. Rommstein, General Surgeon