Could anyone tell me the difference between IBS and bowel or colon cancer before I google it please? For a few weeks now I have been having a day of either normal bowel movements or diarreah followed by 3 days of constipation. Its happening all the time now and I'm freaking out its cancer. I am losing weight hopefully through dieting but I know you lose weight with bowel cancer. Does anyone know if weight loss with cancer is extreme or gradual. I have no blood when I go. Any reply would be mist appreciated. Thank you very much