What Causes Fluttering And Painful Stomach While On Treatment For Peptic Ulcer?

I m currently being treated for a peptic ulcer (1wk in). Taking OTC Prevacid and an Rx coating medicine. I had veggies and turkey burger around 2pm and have been in pain for the last 7-8hours. I m curioushow long it takes for the stomach to empty of food and why it hurts more when the muscle flutters ? Thank you