Is it my period or another cyst?

Me

So I was diagnosed this month (sept 2018) with PCOS.

It started with me having pain and bright red bleeding.

They gave me lo lo estrin to stop the bleeding (I have been off bc since August 2017) but yesterday I had dark red bleeding start. It’s the amount of a period but my period was due two weeks ago (back when I first got the bc to stop the bleeding).

**So how do I know when it’s my period and not another cyst?

On sun I had that pinch feeling like right before I started bleeding two weeks ago.