What Causes Pink Discharge Before Period?

Hi I had sex 6 days ago,my boyfriend pulled out and came. We had sex again 2/3 mins later again without a condom and i'm not on birth control.My period is due in 5 days and i've been experiencing sore breasts for a few days. Today after urinating I noticed a light pink discharge. It wasn't alot but still noticeable. I'm freaking out as I have never noticed this before any other period. Every website I have checked says these are signs of pregnancy. Is it possible that this is just pre period discharge?