Suggest Treatment For Brown Spotting Between Periods

I started taking microgestin in March and since then I ve been having brown spotting in between periods, sometimes its very light and sometimes its a little heavy. recently my period was about a week late before I started but this time my period was very light and my bleeding was brown with a little red and lasted 5-7 days which is normal for me. But a week later I got bad cramps and seemed to be having my period again, this time the bleeding has been more like my normal period. What s going on?