Gastritis Support Group
Gastritis is a medical term for inflammation of the lining of the stomach. It means that white blood cells move into the wall of the stomach as a response to some type of injury. Gastritis has many underlying causes, from infection with the bacterium H. pylori, bile reflux, or excessive consumption of alcohol or certain foods or drugs like aspirin.

I recently had two doses of antibiotics for suspected infection and mercilfully it didn't upset the gastritis. Are you taking a probiotic at all? If not that would be a good place to start. If you are then I would double or triple the dose. The ab gave me heartburn though.
I hope the others can offer better advice.
Hang in there I know how scary this can be.
Cas
while the antibiotics must be taken with food, the probiotics are taken away from food. 1/2 before or 1 hour after. should be on the bottle.
Cas