Help..!

Last night I got up to go to the bathroom because I was having really bad cramps down there (I am not on my period, it is 12 days away). I sat down and the pain got worse and then I felt like I peed myself, it was an awful pain but when i looked down, it was all blood and looked like a REALLY HEAVY period.. and I could not get it to stop and I freaked out and tried to grab a towel and it just kets running down my legs.
I have intercourse regularly (not yesterday though) and a lot of the times with out a condom.
I'm still cramping but not as bad.
Could I have been pregnant? Does anyone know what this was? PLEASE help... I'm very worried and don't know what to do. My SO is worried as well.. Please help.