What Causes Stoppage In Menstruation?

Hi I am 27 years old and have not had my period in almost 4 months now and have been having blood in my stool, which is getting heavier and now has clots in it. I have had a history of abnormal periods, but since being off the pill have had them regularly in the last year until now. My Dr. prescribed me progesterone to get my period started, and I still haven't had it and I am 6 days into my 10 day prescription.