Keith, I have had a similar problem for 2yrs.
I have lost around 8-9kg all together, which is a lot for me as i was already thin even when i wasn't this unwell, GERD wise.
I would suggest getting onto a nutritional supplement of some kind now. These have been a life saver for me.
At the same time try to find things that you feel go down better. This may take some experimentation.
Keep a food journal too with accompanying symptoms, etc.
I have been to several professionals but still haven't gotten much of an explanation as to what my problem is being caused by.
I am going to see an ENT Specialist after the new year. A lot of people say they are good.
Take care and see your doc.
I hope things start improving for you soon.
My GP doc sent me to gastro doc. I had a esophageal manometry test. It is not an ez test but if you stay real still it is not so bad. My test results just came in & they made appt. for me with another kind of doc. I had the same problems as you & I lost weight. Good Luck