This sounds like an ulcer. Blood is a very powerful laxative which can cause dark, tarry stools. However, usually ulcer pain is associated with eating. If the pain is worse or better when eating, then it can be an ulcer depending on the location. Stomach ulcers usually get worse with food, while duodenal ulcers get better with food. I would recommend seeing a doctor for routine screening blood work including H. pylori screening. You can get very strong medications over the counter for acid reflux which will help your indigestion, heartburn, and acid reflux, and overtime could resolve the diarrhea and blood. You can also avoid spicy foods, elevate the head of your head, avoid meals 3 hours before bedtime, weight loss, tobacco and alcohol cessation. However, if you have H. Pylori, you will need antibiotics to resolve symptoms.