I am really sorry to say that : what you wrote here are classical symptom of a ''mass'' in the large intestine. Needs colonoscopy
to see the problem and biopsy
if needed. Biopsy is a must if there is a mass or an ulcer to get a proper diagnosis.
You may require to undergo a CT scan
of the abdomen also.
Rarely this type of symptoms can be found in patients with abuse of laxatives, but you do not get so much mucus in these cases.