I had this same problem for months and I was finally diagnosed with anxiety. I'm on diltiazem and prozac for it and haven't felt the nervous stomach pain for a while now.
I don't think it's heart related. In case you want to talk to other people with stomach problems, at the top of the page is a box "forums." Run your cursor over it and click on health. You'll find a whole long list of forums and there's one just for GERD. That might be more helpful to you. If you struggle with anxiety, there is a forum for that too. Being nervous or anxious has a big impact on how you feel.
You must know the answer for that.