What Causes Brown Vaginal Discharge When Treating PCOS?

Hello I am 26 years old and I have PCOS. I went to the dr two months ago due to normal bleeding. He then did a pap and that came back normal. I now am having that same problem. I believe now it s not blood but more so brown discharge. It s never really stopped. He put me on birth control to try and regulate my cycles but I m still having the brown discharge and I have been on the pill for almost a month and a half! There is no smell and I have no pain it just won t stop. Any suggestions