What it feels like to me

Everybody experiences a panic attack differently. My panic attacks are very very severe and most people with panic attacks do not even have them as bad as I do. Mine cause me to have very bad physical symptoms and then the panic attack feeds upon the physical symptoms and then it sort of snowballs and causes more symptoms which causes more panic.
There is nothing really that sets off a panic attack, it is just something wrong in my head..maybe a short circuit, who knows..but for no reason, out of the blue I will feel my heart start to race. My throat feels like it is closing up, like I have something tied around my neck. I start shaking and start sweating even though I usually feel icy cold. I can't catch my breath. I start pacing trying to get away from whatever it is that is causing me this panic..but it just makes it worse...after a few mintues I start thinking I am dying..if my husband is home I usually tell him that something is wrong, that I am choking that I cannot breath. He now knows that this is a panic attack. On one level I know that this is what it is as well, but on another level I start worrying that maybe this time it really is a heart attack or something awful..if my husband is not home I usually call him crying that I am dying...though I try not to bother him anymore. I often now just get online and try to chat with somebody to take my mind off of it...
Now, for me this can last up to 4 hours or more and then can start all over again..
I usually can medicate myself enough to make it stop but it often takes enough xanax to make me fall asleep for this to stop...
There is not any one certain thing that sets it off though there are a few triggers that I have noticed make me start feeling this way. One thing that causes it is to hear about diseases...I then look them up online and start thinking of have the symptoms of it and that I have that disease. Another thing is watching medical shows like Trauma life in the Er or anything like that. This is very very odd for me since I was a nurse and thrived on the adrenaline rush of that sort of thing but I can no longer watch this sort of show.
One other thing that always causes a panic attack is taking a new medication. No matter what it is, it causes me to think I am having an allergic reaction to it and I will die. Of course I have never had an allergic reaction and now I fear that I am like the boy crying wolf and when I really do have a problem nobody will believe me..
Another big problem that sets off the panic attacks is the globus hystericus that I suffer from...the dr nor I am unsure what came first, the globus or the anxiety. They both started about the same time. Yes I know that the globus will cause me no harm but it feels like I am choking. It makes me feel like my throat will close up and I will choke. I cannot imagine that most people who had this feeling would not start to panic.
I have not had much problems lately with going out. I get out to the gym almost everyday though that is mostly because I feel comfortable there now since I have my workouts set up by a trainer and he keeps track of everything I do. I do not like crowded stores and try to go early or late in the day. With the holidays coming I will probably be staying home and away from the stores. I dont like lots of people and especially lots of kids running around just drives me batty...so I try to stay away from places that are bound to be overcrowded...