Help bleeding 9 days after period

I got off my period 9 days ago my cycle was from the 18-22. I had sex on the 24 and took a plan b on the 26. And now on the 31st im bleeding (I am currently in my ovulation window) Am I bleeding from the plan b or ovulation? the bleeding is just enough to cover a panty liner or tissue when I wipe. Can anyone help???