Hi I Have Irregular Periods..so As Advised By Doctor I

Hi I have irregular periods..so as advised by Doctor I am using Orval-g.starting on 5th day of period to 21days.1 month course was completed and Doctor told to use for 3 months.,waiting for my period...But I notice some side effects like crampings in stomach,uterus..Increase of breast...Sometimes these pains are little high,sometimes low..Is this normal or serious side effect..Can anyone help me