what are the odds?

Okay so my boyfriend and I had sex last night and the condom broke. I've been on the pill for 4 years but this last month I took a couple of my pills late. I was supposed to have my period today. I took plan b this morning (because I was stomach sick all night) but my period was spotting last night around 2am but now there isn't really anything new happening. Could that be because I took the plan B pill so it's screwing around with my system or potential implantation bleeding? I'm really worried