It probably occurs when you consume food/drink. Whatever you consume quickly enters your bloodstream and provokes an immune reaction releasing histamine which causes increased saliva and nasal mucous.
This provides urea for the bacterial infection in your stomach which they use to produce ammonia which neutralises your stomach acid and badly affects your digestion of protein and nutrients.
They are extremely resistant and protect themselves with a biofilm.
I am battling this myself. I have had some success but some of it is far more resistant. It's unidentified which makes it very difficult to beat. I know that mine is not helicobacter pylori which is one urease bacteria. There are others. Efflux pump inhibitors would help but the bacteria need to be know to know which ones will work. Quorum sensing inhibitors would help and prevent them strengthening their biofilm but again, they need to be identified to know what will work. All the unknowns make it extremely difficult to beat them.