Spotting?

Hey guys!
So I had protected sex on the 16th day of my 25 day cycle. We used a condom, did it for about five minutes, he didn't ejaculate and we checked the condom for holes with water afterward.
I'm due for my period in about 2 days, but today I had some blood in my discharge but it stopped, and now it's a tannish, reddish color thick, very little discharge. 
I'm scared of being pregnant I keep reading about implantation bleeding, but then I thought maybe it's just a slow start to my period. Any thoughts?