please please help me

I took plan b on Friday (2/8) and I’m on my last day of my fertile window and I don’t start my period for another week or so. But I noticed that I was spotting but it was dark brown. Ever since the 8th I have had unprotected sex and haven’t taken plan b after those times but I know he didn’t cum inside of me (for obvious reason). Last time was three days ago (2/9). Could the spotting just be from the plan b? Or should I take a pregnancy test to make sure?