I have been having the same symptoms as you and coincidentally for 12 years too. I have seen about 4 GIs, 2 ENTS, 4 dentists etc. I have also done 2 endoscopys, a colonscopy, barium swallow and so many others tests. I have silent reflux which the doctors dispute as reflux tests came back negative twice but am 100% sure I have it especially when I lie down. Hiatus hernia was diagonised but GIs insist that it is not the cause. From my research, I feel strongly that the hiatus hernia could be the cause. There is also somebody who has posted that the problem was solved after he had a surgery for hiatus hernia. Seeing that we both have hiatus hernia and are haing the same symptoms, am more convinced that this is the cause of our problem/long suffering/humiliation etc.
I would be interested in knowing if there are more people having this problem and also diagonised with hiatus hernia.