Sounds like something more like a seed than blood. Blood is not going to stay in your GI tract long enough to solidify into anything hard like you describe.
You don't have colon cancer. Please don't take this the wrong way, but you do sound like you suffer from anxiety and it's not helping your situation.
edit: Have you scheduled the colonoscopy yet?
Post Edited (Wolsnik) : 4/14/2017 8:59:17 AM (GMT-6)