Spotting 4 days after my period = pregnancy?

Cassidy
Okay, so my period ended the 26th of may, but this also happened to be a day that I had sexual protected intercourse with my SO (condom w/ spermicide and pullout method). 4 days pass after this, and I wake up at 1 in the morning to go to the bathroom and I find a little red blood followed by brown. I started to really freak out because I've never just had random bleeding before. I'm 17 and have had my period for about 3 years and nothing like this has happened before. But the thing is, I am kind of new to sex considering i lost my virginity the beginning of April. Is it possible to have implantation bleeding this early? Does it even sound like implantation bleeding? Or could this just be old blood that got trapped when I had sex? Thank you to any answers, I'm still trying to get used to how sex is treating my body and it makes me so anxious and scared. It's such a different world and really opens your eyes to how life can change in a single moment.