My own opinion is that allopathic medicine isn't the best place to treat digestive problems. The medication causes rebound effects, which leaves you in a constant cycle. Natural remedies don't do this. You might try seeing a naturopath and trying to get your digestion into balance rather than just treating symptoms. That pressure you feel can be from the formation of acid, too, just like you're other symptoms, and medications tamp down this acid, but they also force the body to make even more acid, since it's necessary to digest protein. Not a good long-term solution.
Get a second opinion. Make sure there is truly not a physical issue.
Panic attacks can mock other issues. They can feel like a heart attack, a stroke, an asthma attack... Get a referral to a good psyc dr. It took me years to find one, but I have been with the same doctor now for over 9 years, and he's good. Even if it turns out it IS in your head, there are ways to treat it.