Welcome to the gastroenterology community! I sincerely doubt it is cancer. It is probably mild constipation. I would recommend increasing your fiber intake, increasing your intake of fruits and vegetables, increasing your water consumption, and increasing your exercise. It these don't help then I would recommend seeing a doctor.
SEE THE DOCTOR. It could be nothing but my dad died 2 yrs ago from Colon cancer. What you are describing doesn't sound good but it could be nothing. Cancer is silent. Good luck. Rule of thumb, when you have symptoms that make you uneasy or concerned, call the Doc.