I am 27 years old, 247 lb male. I have been having a problem with blood in stool for two years now. Sometimes, I have blood in stool for two or three days and sometimes goes away for months with no blood. For three months, I did not have blood in the stool. Now I started to drive a truck 12 to 14 hours a day sitting on the truck and I started having blood again. I am very scared. I may have colon cancer. My doctor did a blood test on me one month ago including vitamins and minerals and everything came back 100 %. I told her I am scared that I may have colon cancer she said no you do not and you do not need a colonoscopy. How does she know? I have blood in stool for two years now and not in normal shape.