Period twice a month?

I start my menstrual Cycle on 11/12 and ended 11/19 it was really heavy. On 12/04 It started again. I have been having for everyday since my last one, I have alot of cramps also. I have been on Medroxyprogesterone for this whole year because I was in menopause for over 3 years. I have only been taking these pills every other month for 10 days. The months I don't take to pills I don't have a cycle. What could be the reason why I would have 2 cycles in 2 weeks??