Hi My Brother Who Is 30 Years Old Has Had

Hi my brother who is 30 years old has had a history of gastric problems since 2009. Since then he always gets sick once every year. It starts off with nausea followed by pain in his abdomen and vomiting that does not stop for a good 6-8 hours. This past week he was severely sick and had chronic pain in his abdomen coupled with vomiting. He was admitted in the icu unit of the hospital and was discharged a few days ago. Endoscopy revealed the following:
Section reveals three fragments of gastric antral mucosa. Surface epithelium shows no ulceration or erosion. The underlying lamina propria shows moderate chronic inflammatory cell infiltrate comprising of predominantly of lymphocytes. No activity, intestinal metaplasia, dysplasia or atrophy seen. No colonization by Helicobacter pylori seen.
The diagnosis by the pathologist was that he had moderate chronic antral gastritis.
My question is what is exactly wrong with him and how could he take precautions from another episode of this nature happening again?