Brownish color of the discharge usually is seen when there is some breakthrough bleeding
and some collection of discharge inside prior to getting let out. It is common to see menstrual disturbances like profuse bleeding, irregular bleeding, scanty bleeding or inter-menstrual spotting when using oral contraceptives during the initial 2-3 months and settles down later. In the current scenario, you should exclude/confirm pregnancy
through a blood test
as a precaution and see a specialist for further evaluation and management. Hope this helps.