What physiological reasons for peptic ulcer pain are there?

In the past, it was : Believed stress and diet caused peptic ulcers. Later, researchers stated stomach acids (hydrochloric acid and pepsin) contributed to the majority of ulcer formation.Today, however, research shows that most ulcers develop as a result of infection with a bacterium called helicobacter pylori. Acid and pepsin these powerful digestive fluids are believed to contribute to the formation of ulcers.