2 periods, help?

[Scaredat19]

I had my regular period on the 9th, it was completely normal, pms-sore boobs, bloated and aching back, lasted 4 days and 2 days brownish discharge (sorry, tmi). That was Tuesday, on Friday I had unprotected sex (I'm not trying to get pregnant, the condom just fell down the side of the bed and we didn't get it) on Saturday I started having cramps in my left side, like ovulation cramps. And these continued until Monday, then on Monday I started bleeding again, on Monday and Tuesday it was very light and pinkish. Now it's progressed to bright red and very clotty (TMI) it's still going, I don't know what's up and I'm getting my worried, any idea what this might be? My friend suggested implantation bleeding but surely that isn't heavy like this right? Has anyone else had this? I'm 19, not on any hormonal birth control.