Scared: the possibility of pregnancy?

My period is supposed to start in a week and for the past few days I've had mild cramps (I usually have them a week before my period anyways) but today I started having abnormal discharge. It looked reddish orange at one point and now it's either dark red or brown. This has never happened before, but I did take two Plan B pills this month due to BC failure within a week of each other. Could this be implantation bleeding from not taking the pills soon enough (the dirt I took a day later, the second within the hour so I don't believe that to be the reason) or just a change in my cycle due to the pills? All the internet has to say is garbage and I couldn't find anything that relates to my situation. Please help!