freelei

i'm on day 22 of whole30 and i'm not due for my period for another week, but i just now discovered that i'm spotting...which never ever happens. i've been on bc for 5 years and have always gotten my period on the same day. i came on here to search the forum about changes in menstrual cycle and found this, which comforts me a little. still, it concerns me. no one has addressed the science behind it (minus the bit about hormones, thanks to karen a couple posts above). what is going on? does anyone know of any scientific facts relating to this? i just don't want to keep this up if it's bad for my menstrual cycle. if we can't find anything good, i fortunately have a gyno appointment on monday so maybe i'll be able to gather answers from her.