I have always had an irregular period. However this month it came on July 23,2012. The first day was heavy as it usually is but the second day it was light. Now I'm on day 5 which is normal because it normally last 7 days. But I'm on day 5 and its barely anything. The only blood is when I wipe, its bright red and I'm cramping. I took a pregnancy test July 19,2012 which was negative. I have been experiencing a runney nose back pain and I have not been on birth control since I was 17. What's going on, am I pregnant?