Jhamilton,
I do not want this to alarm you, but you should consider it. You may be having what is called atrial fibrillation or atrial flutter. I had incidences of this over several years before it was diagnosed. I didn't have panic attacks, but I did have indigestion, which is common among AFer's. I frequent the site www.afibbers.org, where many share similar symptons to yours, but not alot of panic attacks,however, panic attacks can come from the heart beating irregularly or fast. The next time this happens to you, take careful note of what your heart is doing. Is it beating fast and weak, but regular, or is it beating very irregular, strong and weak. If you can get to the ER, when this happens, they can do an ECG to see if this is what the problem is.
We have found that magnesium (Mg) is deficient in about 80% of the population. Calcium (Ca) is the excitory mineral and Mg is the calming one. See www.mgwater.com for much more information. I am not a doctor, so this advice is for informational purposes only, but you could be well served by purchasing either Mg Glycinate or Taurate, both of which are very absorbable. Do not use Mg Oxide, as it is used in laxatives, and is not very efficient. Take about 400mg per day in divided doses with meals to begin with, and see how this makes you feel. You should also take a good multivitamin, as it contains vitamin B6 which works synergistically with Mg. Try to keep your intake of dairy to a minimum for awhile, as well, and see how that makes you feel. Dairy has a 10:1 ratio of Ca to Mg, which is far greater than what is needed and can overexcite the body.
Hope this helps you.
Richard