Hi. Thanks for your query and an elucidate history. The cramping along with need to rush to teh bathroom to pass motion by nothing comes out is called tenesmus and is seen in cases with a severe form of Colitis or IBS- Irritable bowel syndrome or ulcerative colitis and so non. In such a situation I would advise you the following: -First of all to undergo a course of an antibiotic, metronidazole, probiotic, activated charcoal tablets, anti-spasmodic tablets and see the results. This will help to quieten the colon and give some strength so that colonoscopy can be planned without much risk of perforation or so. -CT scan of the abdomen. -Routine tests of blood, urine and stool. The treatment will necessarily be dependent upon the final diagnosis on colonoscopy and biopsy.