Been there and done that so many times. All the tests come back normal. Even with health insurance, that little habit gets expensive quickly.

I've been told it's possible that sometimes I may be experiencing GERD or some form of acid reflux. But more than likely it's anxiety.

Numbness is a common symptom of anxiety. I read it's because when you're anxious blood rushes from other parts of your body to the heart as you prepare for "fight or flight".
But numbness can also happen if you have a herniated disc or something like that, too.

Basically, it sounds like pure panic to me. But you might have something, non-life threatening, going on.