There are many documented remedies for gastric ulcers. I have used aloe vera gel and deglycherrized licorice ( DGL) Cabbage juice has a great success using 1 liter of juice in divided doses throughout the day.
An old naturopathic formula called Robert’s formula has been used. This is named after Captain Frank Roberts who served in England. He became a distinguished naturopathic physician after his servie to his country
This formula includes marsh mallow root with indigo, American cranesbill, pokeroot and slippery elm/Drs Murray and Pizzorno have added cabbage powder, pancreatin and niacinamide to the traditional formula with good result