microgestin brownish discharge

Hello! So I've been on this BC for approx 9 months now and just recently two months in a row I have black brown with little blood of discharge during the second week of taking them. Feels like it would be my period but  then I get my period the next week according to my pills and cycle. Is anyone having the same problem? I am going to see my doctor soon but I'm worried something is wrong 😬😳 spotting or this discharge thing usually last 3 days. My period is normally 4