A colonoscopy is a simple procedure, where you are given an IV of Valium, that puts you temporarily into the "twilight zone". Then the doctor puts a scope all the way up into your colon, to check for tumors, polyps or colitis. Although it is a rather undignified procedure,It is painless and quick, and you get the results immediately.
With the bleeding, you probably need to have one, just to make sure that everything is OK. Please keep us posted, after you've see the doctor. Best wishes to you.