Spotting/brown discharge, 3 days

Brie • 17, Bisexual, Cali. Bound Flower Child ✌🏼️🌻
I've been spotting light blood here and there, but mostly just discharging a dark dark brown type blood for 3 days, not a lot, but enough that I definitely am becoming concerned. My period is supposed to start on the 24th. Any idea of what this could be?
**I started spotting 12 DPO, if that is important too