Irritable bowel syndrome (IBS) is a functional disorder of the large intestines. IBS does not indicate presence of an organic lesion on the intestines. Rather, IBS indicates a distrubance in the reflexes that control the intestinal peristaltic movements. IBS is related to stress and anxiety and is considered to be a psycho-somatic disease. In your case, organic lesions (ulcers) are found in the colon. Therefore, it is not possible to say that all your symptoms are due only to IBS. Crohn’s disease and ulcerative colitis are inflammatory diseases (probably autoimmune) with unknown etiologies that can be confirmed only with a biopsy. During a biopsy, a piece of tissue is taken from the lesion and examined by a pathologist. Both diseases are also connected with anxiety and stress.