Late period, Brown discharge 😐

I'm a slight confused.. my period is very scheduled. I know what date AF is coming, and what date she leaves... Every... Single... Month. But, this month on the other hand is Different. AF was 4 days late, then was a VERY light brown discharge. I'm on day 4 of this light brown discharge that doesn't fill up a pantyliner. Anyone else have this problem or know what it could be?