What type of discharge is this?

I’ve been on birth control for about 3-4 months, my periods have been the same, just a little lighter. 2 weeks ago, I was on the second row of pills and I started my “period”, it was all just brown...no blood at all. It lasted about 6-7 days then stopped. And now I’m on the last row of pills and I’m getting brown discharge again. Does anyone have any idea what this is or why I’m getting this? Is it my period...twice in one month?