MENSTRUATION OR DISCHARGE?

Hello! it’s my day 25 of my cycle and I got this thick black/dark brown. I don’t know if this is my period already because it’s lighter than my usual period (and there’s no red period blood). This lasted for four days like my period. (My normal period is usually red and heavy) can somebody help me? I’m so anxious right now.

It’s impossible to be pregnant right? We just did some fingering during my last period.