Is Hysterectomy Necessary For Irregular Bleeding After Periods?

I am 49 year old, I have two fibroide in uterus, measuring 5 cms and the other one is of 2 cms. Firbrode developed eight yeras back. All these years I am getting my periods regularly and the bleeding stopped on the 4th day. In the month of April after the 15th day of periods I have bleeding and I consulted gynaecologist, she prescribed Gynae CVP and Pause mf. The bleeding stopped after the 5 days course of medicine. My periods was normal afterwards and I got period once in a month. Again in the month of October again after my regular periods and an interval of 5 days I have bleeding and as advised by my doctor the same treatment I took, even after the 5 days of course there is still spotting . Please let me know the reason, Is Gynae CVP is an estrogen then why it is been given to control the bleeding. Is that I have to go for hysterectomy ?