cold symptoms and dark blood clots between periods

It has been two weeks sinse my last period ended and today I found that I am having my period again accompinied by some dark blood clots. I also have a bit of a cold that started two days ago. Could this be because of a "morning after pill" that I took a week ago ? I have taken it before many times and never had this affect. If not that, what are these symptoms an indicator of ?

Thanks !