Clotting after period?

I noticed something that seemed very bad today.  After I was done having sex today, and my partner came out, a medium red-brown clot came out as well.  I'm not sure why.  It's been a few hours and I'm STILL lightly bleeding dark and thick.  I'm guessing it's one of these reasons:

1.  Maybe my hymen broke, again?
I was really tight and I hadn't had sex for a couple days so I thought my hymen couldn't brake again.  I know that they can heal, but I'm not sure if it's possible because of how sexually active we are.  But then again, and here's the embarrassing part, I had been doing exercises so I would stay tight (and I mean A LOT of exercising).  So I thought that maybe it would give it more of a chance to close up.  That still doesn't explain the color though.  But during the beginning of it I had severe cramping, or something.  It just hurt really bad because I was so tight.  

2.  I've read about implantation bleeding.  
This would explain the color. On Wednesday we had sex 3 times.  One of the times I went for too long and as he was pulling out after he ejaculated, the condom came off.  I caught it before it went far up inside, but it wasn't too bad.  This is what scares me.  

3.  I've stopped taking the pill, I've heard this may cause clotting.
I have been taking an oral contraceptive for the past two months.  Last Sunday I was supposed to start again because my period ended last Saturday.  So I take it on Sunday and Monday but then I completely stopped because I lost them, yea great job, I know.  I've had sex last Saturday (x1), Monday(x2), Tuesday(x1),Wednesday(x3), and Today, (Saturday x2).

Note:  We've used a condom, every time.

Please only respond if you really think you know the answer.