It is good that you have seen a cardiologist and gotten a clean bill of health.
Twice I had what I was sure were heart attacks, same symptoms as you described and in both cases I felt that I was dying, once I called ems to the side of the interstate, and once my terrified wife drove me to the ER, both times I had clean EKG's, People told me they sounded like panic attacks, to which I was sure they were full of shit because how could something that had such strong physical symptoms be just in my head, right??
Since then, about 5 months ago, I have accepted that I have anxiety/panic disorder, and I have seen a behavioral therapist and am now taking Lexapro
20mg everyday, I have gone from having about one level 10 (heart attack-like) panic attack/day to zero bad panic attacks and about 1-2 level 3 anxiety spells/week
The good news is that the success rate for treatment of anxiety disorder is about the highest of any mental health disorder.--I am down to one session a week with the behavioral therapist, but there is no way I'm quitting the Lexapro anytime soon.
Drugs: SSRI's like Lexapro are now the gold standard, they used to give people benzodiazapenes like Xanax
, now these are reserved for severe cases that don't respond to the SSRI's because they can cause dependance and they mellow you out almost too much to where they alter your personality.
However SSRI's take a while to start working all the way, the smart thing is to start at 5mg, then 10, 15 up to 20, spending at least a couple days or more at each step, also they will fool with your serotonin levels and you feel "something" happening, some people report feeling a little worse the first day or two when they first start or tritate up to the next dose.
I'd ask your GP or a psychiatrist
to see if maybe he'd give you just a few Xanax as a stop gap, and start an SSRI, combine this with some behavioral therapy
and you are going to start feeling a lot better really soon. Good luck!!!
Also any good bookstores will have books on anxiety disorder, just make sure it is one written from a psychiatric/behavioral psychology perspective and not "heal yourself with herbs, Jesus, Scientology, etc.
Also, Google: "Panic + Breathing Exercises" ----This is something you can do to start feeling better right away!!!