My Boyfriend And I Have Been Dating For A Few

My boyfriend and I have been dating for a few years. last Wednesday 10/29 we had sex but the condom broke so I took plan b the next day. I had to take it with monster because it was the only drink I had. Today 11/6 I have light spotting. I already had my period the week of 10/16. And my period isn't supposed to come until 11/22. My question is, Is the spotting side effects of plan b or is it implantation bleeding? Light bright red. Thank you so much.