A friend of mine suddenly started getting panic attacks, and went to the doc. they found a cyst on the adrenals, which was provoking the adrenals to push out spurts of adrenaline.
Might something like that be a consideration? There is also another condition which causes the adrenals to do that, ~ it begins with P, but I'm damned if I can remember what it is. And I can't look it up, if I can't remember the name.
You can ask your doc though, and if it is that, it can be tested for pretty easily...