Have you concidered the bacteria Helicobacter pylori? This bacteria is now attributed to the onset of stomach ulcers and it gives heartburn.
I came down with a bleeding ulcer 10 years ago while in the Family. I of course didn't get it thouroghly checked up on.
This week, I took a breath test to see if I have the H. pylori bacteria. I'll let you know how it turns out.
It says on the internet that from 60 - 80% of the world carries this bacteria. Some people have no symptoms. If you don't get it taken care of it can get worse and develope into ulcers and stomach cancer.
They don't know where it comes from from, but unclean living conditions is a good source.
When I got my ulcer, I gained weight for 3 years. I always had heartburn as well.
I read that if find out you have the bacteria there are some good natural remedies for it, like something called "Manuka honey" and another one that starts with the letter "m".

I heard from our friend a doctor that this bacteria is very strong and is likely to return to your stomach. But garlic really on a daily basis helps keep it at bay.