Period 1 day late with light brown spotting

Rachel

AF was scheduled to arrive today. It’s usually right on schedule. I noticed two brown spots on my panty liner but nothing when I wipes or in the toilet and nothing since then. Negative pregnancy test yesterday, but I’m had no regular period symptoms. I’ve had a headache for 5 days and want nothing but Mexican food. Does this sound like implantation bleeding or early pregnancy? When would you test again?