Troy Ulcer: Ulcer is a sore that develops on the lining of the esophagus, stomach, or small intestine. Ulcers occur when stomach acid damages the lining of the digestive tract. Common causes include the bacteria H. Pylori and anti-inflammatory pain relievers, including aspirin. Ulcer is a sore that develops on the lining of the esophagus, stomach, or small intestine. Ulcers occur when stomach acid damages the lining of the digestive tract. Common causes include the bacteria H. Pylori and anti-inflammatory pain relievers, including aspirin.