My Husband Has Experienced Tightness And Pressure In His Upper

My husband has experienced tightness and pressure in his upper abdomen after eating and the discomfort has lasted several hours. It has affected his sleep. It doesn't happen every day but it has happened in the last two weeks about 4 times. He also said that his stool has been smelly and that it has been dark and a little mush. This is not usual it is usually light brown and not really smelly