I was having the exact same symptoms and then my gallbladder failed. In the time it took me to get on a Charity Care program at the local hospital, my body began bipassing the gallbladder. Prior to this, I had severe gagging, especially when doing things like brushing my teeth. They treated me for GERD and also scheduled me for gallbladder surgery. I had the surgery on Thursday and I feel like a different person. Very little bloating (which will go away as I heal), no gagging, no vomiting/acid refluc, and the cough that i have had consistantly for a year, is gone. Not sure it is the same with you, but maybe having your gallbladder looked at, if you havent allready might help .
I myself am getting weary of a 7 year cough. It is getting to the place that after I eat I cough so hard I vomit. Other times of the day I have coughing fits. I am currently drinking a glass of water with baking soda. It alkalizes the stomach and seems to calm things down. I am just in the experiment stages. I have also cut out wheat and dairy. We'll see.