Mastica is a herb and it has been successfully proven to kill the hpylori bug! this can be the cause of gastritis and ulcers. Docs usually give you a long course of antibiotics but it tend to come back as our bodies become immune to them.
If the cause of your gastritis is the hpylori bug then mastica would be great!! so it wouldnt hurt to try it, your doctor should really test you for that in the first place to determine the cause of the gastritis/ulcer but many dont. Gastritis is also often caused by drugs such as asprin, my friend got gastritis by taking things like ecstacy to much over a period of time and that damaged his stomach lining.
But if it is the hpylori bug then the gastritis usually heals very well! so get your doc to test you for that and get some mastica (mastic gum) it is a bit pricey but is sold on the net and is very effective!
So LEELEE04 get your doc to test you for that bug and if you have it get some mastic gum if not carry on with the drugs and my other suggestions!
I have functional dyspepsia which is a chronic stomach prob with little understanding and no treatment so i envy you lot with gastritis!! sounds stupid but at least you have a ton of options to get rid of it!!