Brown blood?

I'm on my period, on day 3 of 7, and when i last went to the bathroom, my pad had brown/almost black blood. It was a normal amount for me (as in not heavy or light), and I'm pretty sure it's not just old blood because it's not the beginning of my period or the end(that's what every article i found online said it was - leftover blood and it would only happen at the very beginning or very end of period.) And i know it wasn't just blood that had dried because I'd changed my pad not too long before. I can't find amything online & don't have an OBGYN or the money or health insurance to go see one, so I figured I'd ask here what it could be. xx