Hi. Thanks for your query. 4 months is a long time to suffer from pain in abdomen. You have nausea, feels like knife cutting in the stomach, bright red blood in stool, consulted 2 Doctors and have undergone many blood tests. The most probable reasons for for your symptoms are: Acid Peptic Disease, causing stomach ulcer or duodenal ulcers, can be a cancer too. Your another problem of fresh blood in the stool can be due to Hemorrhoids. I would advise you the following: -Upper GI Endoscopy to see for ulcers / cancer and so. -Colonoscopy to see for the fresh blood in the stool and to know the reasons like piles, cancer, mass , polyp and so on. If required biopsy will be done. -CT scan of the abdomen. -Examination of the stool and urine as you have already undergone many blood tests , which may be normal as you have not mentioned anything here. The further treatment will be as per the reports; till then get started on: PPI like Pantoprazole Antacid liquid at 3 hourly interval. Soft bland diet and small frequent food. Avoid all the foods and beverages that instigate or enhance the problems. Laxatives if the stools are hard. Sitz bath in a tub with warm water. 5-day course of an antibiotic and metronidazole, probiotics, symptomatic and supportive., If all the investigations are normal, you may have to undergo MRI of the spine as there s a possibility of prolapsed inter-vertebral disc causing such symptoms of knife cutting inside your stomach.