So, the morning after pill is really well known for causing irregular bleeding after you take it. It's a big huge dose of hormones which is how it works. This irregular bleeding which includes not getting a period when you think you should, spotting, bleeding heavily, etc. can go on for up to 3 months after you use the morning after pill. I would guess that you are not pregnant and that is the case. You would get a positive pregnancy test 2.5 weeks after the sex you are worried about so can take a pregnancy test but really believe this is just post morning after pill side effects.