I'm a distance runner. I run 75ish miles a week. I do races that are 100 miles. I've had bowel issues for the past 2 years (since I've started running). Random bleeding, random mucas, and I have to poop a lot. I've been told that it's from my large amounts of exercise. I'm worried I have colon cancer (even though this has been going on and off for 2 years). Do I need to worry about this?