In May 2015, I took Plan B after a condom slipped off. I was nearing the end of my period. I took Plan B, noticed my menstrual cycle stopped briefly, then finished. I got what I believe was my period on June 2nd, 2015 (approximately a week earlier than usual). I have had protected sex after this time. During mid-June, I noticed unusual breast pain, a breast size increase, nausea and stomach pain. Currently, from June 2nd, my period is 18 days late. I've taken two pregnancy tests and they have both shown to be negative. Could Plan B cause abnormalities in my cycle this long after taking it?