Hey if your still needing help, it's probably just an internal hemorrhoid or something simple like that. Supposedly, they are fairly common with people who sit in chairs all day long without cushions, as well as males ages 20-28 and 60+. If there was no pain associated with it, it could be that it just burst and the source of the blood. Was the blood Lighter or Darker Red? The color can tell you roughly where the bleeding occurred within your intestinal track. If there was pain, it could have been an external hemorrhoid and have had bright red with it. If it was a hemorrhoid, expect a LOT of blood initially, but pretty much none after about 16-24 hours. If there is still blood after that point, it's probably something else and could bleeding from within the intestines (as i said, color would help determine this), ulcers, food poisoning, diabetes, and about a billion other things. But most commonly, it's just Internal Hemorrhoids, especially with people who sit at computers all day in chairs with inadequate cushioning.
Now, you might ask, Why does Pterrydactylhis know so much about this?
Well, Since I'm typically the most responsible among my friends, I end up taking people to the hospital the most. Thus, I've been slowly learning medical problems and terminology from both being in the room with them (such as how i learned how to locate necrotic tissue on legs and feet), or in the case, from the reading material in the waiting rooms.