Unsure about symptoms, might be GERD or other esophagus issue?

For the past month, I have been dealing with discomfort where my chest meets my abdomen. It was very strong when it first started. Here are the symptoms:

- Mild discomfort that seems to get aggravated at random times

- Very burpy. More mild, but still seems to happen a lot.

- Pale brown-green stool

Over the past month, the discomfort has gone down significantly. Here are the biggest things that I have done:

- Doctor prescribed 40mg of Pantoprazole

- Eating in and cooking in way more

I saw a GI specialist yesterday and he seems to suggest that the discomfort might be coming from acid reflux, but I don't really feel heartburn. Though, not the same way I do when I eat food too fast. If anyone has any suggestions on if this is GERD or potentially something else, I would love to hear your feedback. Thanks!