Can Bubble In The Ovary Causes Pain The Stomach Or Femilon Pills?

Hello Doctor
There was irregularity in my periods, after consulting doctor I started taking femilon pills for three months and now my periods are regular..!! This all happened to me a year ago. Now my question is, last month I had continous bleeding problem.. So I took femilon pills last month and this month I got my period on time but Iam having sever pain in my stomach. Also doctor said, that I got a bubble in my right ovary. Is that anything serious?? what actually it means?? Could you please reply to my question..