Hello, You are having burning sensation on the anal area. You have black stuff in the stool. You have history of half colon removed and rectum. Rectal discomfort is commonly due to acute diarrhea that is associated with infections. Rectal irritation occurs due to repeated excretion of watery stool and the more frequent wiping after a bowel movement. Moisten the let paper before wiping to avoid injuring the anus. it is a delicate area and injury may cause burning sensation and discomfort. Such sensations of discomfort may worsen upon prolonged sitting or during defecation. Avoid prolonged sitting in the toilet. Use of sitz baths can provide relief. Clean the anal area during bathing and dry it thoroughly afterwards. Toilet papers should be soft and of good quality. Such sensations are usually caused by problems within the nervous system, it is also caused by pressure exerted on the rectum by the surrounding tissues. Black specks in the stool can be due to various conditions like GI infection, parasitic infection, etc. Get Stool examination (R/E and C/S) done. You will be treated accordingly. Stay away from addictions if any. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician