Brown Discharge as a Period?

Jade

Hello! I've been having brown spotting/discharge since December 5th. My periods have always been irregular, but whenever it comes, it is always normal in color. I (kinda) ruled out pregnancy because I tested hella negative on November 20th, but I did have unprotected sex on December 1st. Is this brown spotting supposed to be my period or is this something else? Thank you!