What Causes Slight Cramping And Little Discharge ?

Hi I m on ortho tri cyclen lo that i take religiously every day. I normally get my period on the third inactive pill. This month in the days leading up to my period i had slight cramping and tender nipples. On the day my period was due i got very light in amount brown with a little red discharge, not enough to require a tampon. My breasts no longer hurt but still have slight cramping. Is this discharge normal or should i be worried that something else is going on? Thank you