My cycle is 24 days (spot 3 days, period 4 days). 1 week ago i began spotting 1-3xs everyday, light pink/red. my period is due today, so i took a pregnancy test - it's negative. what may be happening?

Late period: It's hard to say why it happens, but sometimes we are just late for our period. Even if it's never happened to you before, it could be happening now. Things like medications, stress, travel, changes in your weight, can all cause a late period. If your pregnancy test is negative, repeat it once per week until you get your period, to be safe. If no period for a whole month, i would see your gyn doc.

Birth control?: Birth control can cause some of these issue. So can uterine changes. Best thing to do is call your OB gyn doctor and discuss. Better to be proactive because you know your body the best and your concern is enough to make that phone call.