What Do You Suggest For Spotting With Brown Discharge When On Microgynon?

I am currently taking microgynon 30. And have been for 2 years. I have never had a problem with it I till this week. Every month I take the 21 pills and have a 7 day break. This month is like no other. However I seem to be having some spotting/brown discharge and have been for a week now. It is very minimal. But I have missed no pills. Why is this happening? I am very worried xx