Blood in stool (today). abdominal pain (for months) but was ibs: goes away after bowel mvmt. did fit 2 mo. earlier, clear. worried for colon cancer?

Bowel symptoms: Bleeding per rectum needs immediate attention by a physician who can perform digital rectal exam and colonoscopy since you have symptoms worrisome of cancer see doctor asap.

Unlikely: At the age of 20, unless you have an underlying familial syndrome, it is unlikely to be colon cancer. More likely are things like inflammatory colon conditions such as Crohns or ulcerative colitis, you should see a gastroenterologist.