Brown smelly discharge, birth control?

I just started taking birth control pills because I will be getting married in roughly 3 month. I am not sexually active either. I started my pill the first day of my period as my doctor told me to and am now about 12-13 days after my period but have not stopped spotting. I am having thick brown discharge that has a foul smell coming from it and am not sure why or what it could be from or if I should go see my doctor.