Cant shake feeling like I'm gunna die (long post)

I dont do this kinda thing ...like in general posting to message boards of any kind but I see alot of similar cases to mine its comforting gives me confidence to throw my personal thing I got going.

For the past month or two I've been dealing with some heavy panick attacks to the point that I was sent to the ER the reason behind my attacks is I can't stop thinking that everytime my body achs or my heart beats a little faster from walking up stairs it could be anything boom that's it ima gonner I'm gunna die and I start thinking how I don't wanna leave my wife alone how I'm not ready yet about how I dont wanna miss my first kid being born and at this point I'm sweating huffing and puffing and feel so out of control of my own body it's a little scary. Now after going to the er determined somthing was wrong just to have a doctor give me that look that are you sure your sick ? Saying all the ekg's are normal and no signs of heart attacks and your BP (somthing I also freak out about) is normal. It's got to the point to where I would have my preggers wife drive me to the er just to sit outside cause I was freaking out and after awhile I would be ok , now mind yall I am young I hit the gym or use to before this started up I stopped going cause I was scared to raise my heart rate but I was going everyday after work about 4 to 6 times a week also my diet is ok not perfect but ok , but as of today this date I've been to the er 4 times with no results of any problems , I never had this sort of thing happen to me I'm not the type to be acting like this idk but my question would be how can I regain control and stop thinking every little thing I feel is a insta death. Tips and tricks that I can use to help me get over this hump would be greatly appreciated