Did they say on your PH study what percentage was gas reflux? You do have a high demeester score. A peptest which you can pay for privately in the UK (spit in some saliva tubes) will show if you have pepsin in your mouth - pepsin is only found in your stomach, so if the sample is positive you are having LPR - silent reflux.
If your consultant suspects that gas is the issue then has he put you on a motility agent such as domperidone to see if that helps?
You also have to remember that a manometry is just a snapshot of 30 mins of your day, I can guarantee you that if you had 3 done over 3 separate days you would get 3 different results.
Has your consultant offered you any alternatives?
Hypothyroidism, Glaucoma, Dry Eye Syndrome, Positional Vertigo
"Some days I'm on top of the world... and on other days I'd like to be 6ft under"