Gastro problems for a month?

My husband ate a hamburger (medium-well) about 3wks to 1 month ago. By that night, he had been complaining of stomach pains and went to the ER (abnormal!). Doctors told him, every since, that they don't suspect it to be from the burger. He's had blood drawn, symptoms discussed, and is not awaiting his appointment to see the gastrologist. He was put on nexium and phenagen for nausea but he is a police officer so he cant take it while at work. His bowels did some chaging, and he has not been eating things except light grilled or baked foods, a side salad occassionally, activia yogurt, and drinking water. He's lost 7 lbs since, says now that his stomach does not hurt, but rather soreness on his left side by his rib cage and in his pelvic area when he gets full or uses the bathroom. His family has a history of GERD and acid reflux, indigestion, and doctors all say its just a bad cause of gastritis. Can any MEDICAL professional help us?!