I have the antibiotic resistant form of Hy.Pyl. which from time to time used to give me really bad gastritis unless I do several things which I have worked out over time. Try the following:
German remedy - roll chamomile tea - i.e. make some strong chamomile tea, drink it (not too hot or it will irritate the stomach), then lie on your right side for at least five minutes, left side for five minutes, back for a five minutes and then your front for five to ensure all areas of the stomach are bathed. This is very soothing but you need to do it on an empty stomach, several times a day.
Manuka honey is also very healing on the stomach - but you must take it slowly off the spoon as any heat kills the antibacterial/antiviral element. (As well as healing it also kills H.Pyl if that is part of the problem).
Mastic gum (can be obtained in capsules) is a centuries old remedy for stomach problems. It does, however, also kill candida so if you have that you can experience unpleasant "die off" symptoms. If you try Mastic Gum drink plenty of water through the day so help avoid any problems.
If you can bear to drink it cabbage juice has been shown in research to help - I've never tried it though.
Hope you can find something which helps you - I know how unpleasant it can be.