Hi amezamez. Sorry for all your suffering.
Much of your suffering is because of the poor choices you have made
so far... and you know this.
Gastritis can be diagnosed from symptoms alone, however, antibiotics should have been prescribed along with the omeprazole to fight H.Pylori, the most common cause of gastritis.
I don't know if what you're taking now is doing anything for you.
My opinion is that you can do many things on your own, starting with cutting out the "crappy" foods. Put nothing made in a factory in your mouth
and the same for fast/packaged food. If you don't, you are predisposing yourself to a lifetime of suffering and illness.
So optimize your diet, eating fresh healthy foods. Take probiotics, apple cider vinegar, aloe vera juice and virgin coconut oil to help cure your suspected gastritis. Black licorice tea or supplements also help.
Theme parks may not be the ideal place to hang out, but if you do go in the future, just make sure you have eaten a good nourishing meal before, as the food choices there are less than desirable for anyone's health.
I forgot to mention that the apple cider vinegar should be raw, unflitered organic with the "mother" in it.