Okay so I protected sex for the first time on August 16th. Then I took plan b because I thought I might have slipped then a week later August 26th  I got what seems to be a period but I'm not sure. The cramps felt like menstrual cramps but much worst then usual. I had horrible back pains that occurred in both my upper and lower back. I never get back pains in my upper back before not ever  to be honest. This period was the most painful period but why did it only last two days. I find this to be very weird