Main symptoms of an ulcer: If you feel better when you eat or drink and then worse 1 or 2 hours later it may be a duodenal ulcer. If you feel worse when you eat or drink it is possibly a gastric ulcer. Ulcers may cause stomach pain that wakes you up at night. You may feel full fast. A heavy feeling, bloating, burning or dull pain in your stomach is also common. Vomiting and unexpected weight loss may also occur. Please see your doctor if you are experiencing pain or unexplained symptoms.