I too have gastritis and GERD. In my case the gastritis kicks in when I am under a lot of stress. This then ramps up the GERD and I wind up burping, metallic taste in mouth, dizzy, headache, pains in chest, stomach and shoulders.
I had an endo in March which confirmed the diagnosis. They found hiatal hernia (suspect it may play a minor role due to the age of the hernia), gastritis (unable to find root cause-all results for known culprits were negative other than stress). They had to take 4 days of bed rest and 40mg of Prilosec. Within 72 hours the symptoms were gone.
I don't eat a lot of greasy fried foods, have added more veggies. I find that fresh veggies impact me less than frozen or canned. Certain fruits and veggies appear to increase my symptoms. These are: too much caffeine (although 1-2 cups of coffee don't bother me), the cauliflower type veggies, tomato paste, and most fruit juices (sweetened) cause me all kinds of problems. I also found that a handful of cashews, almonds, pecans or walnuts also help. I am working on losing weight and excercise 2-3 times a week for 1/2 hour.