Stomach cramps and diarrhea (with a little blood) 30 min after every meal for 9 days. no other symptoms. could it be a symptom of colon/bowel cancer?

Less likely ca.: fAbdominal cramps and diarrhea are symptoms that may come with various disease, including gastritis, food poisoning, irritable bowel syndrome, parasitic infections, diverticulitis, etc. Intolerance to milk products or lactase insufficiency is another cause. If symptoms continute should consult internist or gastroenterologist. Diagnosis of cancer would be much less likely.