You need to have a physician provide you with medical therapy to heal your ulcer. You also need to know if you have an infection with H pylori and if so you need to be treated. Those are much more significant than any dietary changes.

This is debatable but is outside my realm of nuclear medicine. Typically a bland diet is recommended. Sucralfate is sometimes given to coat the stomach.

Diet and ulcer are not related. Foods do not cause or exacerbate ulcers. A healthy diet is one that protects your heart (avoids coronary artery disease) and avoids hypertension and diabetes.