i am having my first colon test and i know i have to have it since my mother died of colon cancer and my brother a yr older had part of his small int.removed because of cancer.my feer is that i have had abnormal bowl movements for a couple mths now and in feer i would just say it was nothing.the oder has changed to a burning rubbery smell that is not normal for me .sometimes i will not have a movement for a day or so then its loose and just not normal could this be a cancer?