What Causes Abnormal Menstrual Bleeding Post Tubal Ligation?

I got my tubes tide in October of 2014 and didnt have a period up until now recently march 2015 i started clotting and then woke up one morning with heavy bleeding, i stop through out the day spot for a little bit and when i lease expect it I start heavy bleeding again with lots of cramps on the right side I do have a cyst on my right ovary and its causing pain but Im not sure why i been bleeding for 3 weeks now???