Why is St. Elmo the patron of stomach problems?

St. Elmo was tortured and killed in the Roman province of Illyricum, after boldly preaching and converting numerous pagans to Christianity. Legend says that his stomach was slit open and his intestines wound around a windlass. This version may have developed from interpreting an icon that showed him with a windlass, signifying his patronage of sailors.

Besides his patronage of mariners, Erasmus is invoked against colic in children, abdominal pain, intestinal ailments and diseases, cramps and the pain of women in labor, as well as cattle pests.