Go see your gynecologist to figure out what's causing it. You shouldn't bleed longer than a week, so something's up hormonally or otherwise. You need to get checked out.
You seem to be having the symptoms of metrorrhagia(heavy periods). Various factors causing it are endometriosis,ectopic pregnancy,hormone imbalance,endometrial hyperplasia,polyps,use of IUD’s and depo shots, sexually transmitted diseases,PCOS and benign and malignant pathologies of the uterus. It may be due to worsening of PCOS and you may need to start the treatment.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.