it could be a lot of things. hemorroid, polyps or cancer. i don't mean to scare you but you need to see your doctor and tell him what is going on. more than likely he will want you to have a colonoscopy. this is where they put a scope inside your colon to check things out. simple procedure, done as an out-patient.

I had the same problem about 2 years ago. And this is going to sound TOTALLY insane but I swear it's true.

I went to the doctor, he said it was probably hemmorhoids but he sent me to a gastroenterologist. I had a colonoscopy and he says "well it could be colitis but it's definately not Chron's disease, here take this medicine" (which I forget what that was). Well that didn't fix it. So he took another colonoscopy and then I go in his office and he shows me this tiny little picture and says "you see that, I think it's chron's disease, here take this prednisone" Which I did, and gained like 25 pounds and it didn't fix it, so since I assumed he had no idea what was going on I quit going to him. After a couple of weeks it just went away by itself, and only seemed to start happening again on occasion. So I started paying attention to what I was eating/drinking around the time that it was happening. What causes it? Coca Cola. I know, it sounds incredibly stupid and doesn't make sense and I think Coke is the best soft drink in the world, but I've tested it 4 times to make sure. If I drink just 1 can of coke a day for 2-3 days it comes back. I haven't had a Coke in 2 years now and I haven't had the problem in 2 years. It doesn't happen with any other soft drink or food, so I don't know what the deal is.

The first thing I'd do is go see a doctor, but also try removing things from your diet, something different every couple of days and see if it clears up. If you drink a lot of coke, try that first.

Just wanted to ask a question for curiosities sake...

Does Pepsi not cause the same problem?

Nope, not Pepsi or Dr Pepper or even Sam's Choice Cola or anything like that. In fact I switched from Coke to Pepsi/Dr Pepper as my soft drinks of choice. The only thing I've found that slightly causes it is Mr Pibb, but I have to drink a lot of it and even then it doesn't really cause too big of a problem. But i've heard that Mr Pibb is Coke and something else mixed together but I don't know that for a fact. It's made by coke, so I guess it's possible.

just an idea, stress can well be the cause of this bleeding. I had the same issue and it was all stress related. stress can be a big impact on one's body. my friend had lost big portions of hair on his head, all due to stress.

If the bleeding continues for about a week or two...then you should certainly head over to see the doctor. now even though this thread is well older than acouple weeks.
...any future viewers of this thread, keep in mind that sometimes the strangest things can be caused by stress. Don't automatically think it's cancer just because you bled for two or three days... as well, don't dwell on it. most cases are over exaggerated.