Sling for swatch

I'm confused...dark brown discharge, unprotected sex, answers please? - dark brown poop and missed period

I am 17 and on the pill for almost a year. In the past month (March) will not take because I could not afford to fill my own. Throughout the month, my friend and I had unprotected sex (stupid I know ...) almost every day with the withdrawal method. I get my period at the beginning of each month, but my last period was not (I guess because I was not taking the pill, before Jesus Christ throughout the month, and my body is confused). After I took my game and now I'm back on the pill. About a week or two ago my friend and I had a bit (we are the children ... stupid I know) and it was without a condom. So then there was a strong fish odor out of my vagina. It took several days and couldOdor through my clothes were so strong. I had cramps accompanied by the smell, which are still available. It's like I have my period, but I am not. Last week, when we had sex I went to the bathroom and noticed a little blood. After that I have with dark brown and the flow of menstruation. Discharge almost looks like shit (gross) and has no smell. I missed 2 SHPT few days after my period (about 3 weeks) and if it was negative. I also have a detection kits Vagisil check for an infection and was normal.
I have no idea what was going on and I said to my friend, we need to make a use of condoms. I feel stupid and a little scary if someone could me some ANSWERS I'd be very happy.