What Is Causing Irregular Menstrual Bleeding?

I have a cyst in the left ovary. At present I am taking Gonablok 200 mg thrice daily, on doctors advice from 14.10.10. My last monthly period was on 10.10.2010. But, suddenly from 27.10.10 there were occasional bleedings which continued up to 04.11.10. Since then bleeding has stopped, but there is no sign of monthly period even after 32 to 33 days. Will you please explain? We will be very much obliged.
R.K. Chakraborty