I know what you are going through and feel your pain. I have gone through many years of the same exact stuff as you. Started with feeling physically sick, went to a bunch of docs, all testing came back fine, and someone finally mentioned it could be this so called "panic/anxiety". Perhaps it is panic and anxiety but the truth about most panic and anxiety conditions is that they actually come from some medical condition or metabolic problem. We just don't have the technology or diagnostic tools to to really identify what is actually causing the problem which in turn is actually the cause of your panic and anxiety. Doctors will tell you all kinds of 0103 about it being in your head, physiological this and that, and it has nothing to do with any of that at all. That's just a way throwing it back at you cause they don't have the real answers for you. The medical community is real good for doing that and have been doing that since the beginning of time. They know a lot less than the people think. In fact, aside from dealing with heart problems and cancers quite well they know close to nothing about anything else. So my point here is this... don't blame yourself for what you are going through. Don't worry you have many ignorant people, physchologists and medical professionals that will do that for you, so why do it to yourself. Just go easy on yourself and be patient,.. you will come out of this and get better.
The other thing is try to stay focused on things outside yourself.... connect with people, sports, music, working out, whatever your into, just stay busy. My personal opinion is to stay away from psychologists as they cause you to be more introverted and will likely cause you to be more analytic and do cause too much rumination. From reading your post you sound very aware of what is going on with, so you don't need anything that forces you to sit and go through this stuff over and over with them. Its a pure waste. There may be some other folks on here that will completely disagree with my suggestion, but physchology is another entirely crap field with the downside of forcing people to become too analytical. Unless you have absolutely no family and friends you can talk to you than I really discourage anything like this. Just get out there and live.
I know you had a bad experience with Zoloft but it may be worth trying a couple more SSRI's.... sometimes people eventually hit on one that helps. They didn't really help me and I've always had adverse reactions to all them, but I do respect that they can work for some people. Try some natural things... give em time to work.... fish oil, b12, valerian root, magnesium, etc. Again... sometimes these could end up helping so try one at a time and go slow. But the all #1 rule I have for you is... is try to completely stay off benzos. These are an absolute disaster for people with panic and anxiety. They have a horrible backlash, downregulate your GABA recepotors and ultimately end up causing your anxiety to become much worse in the long run. Actually even the rebound in the short run can be causing more than half your problems already. It takes a lot of time to recover from benzo use, so I don't know how much you used or how long, but consider some of your problems could be realted to that if you have infact been using them for a long time. Benzos become hightly addicitive... not in a physchological way, but more so in a physiological way, meaning the body starts to panic and have anxiety when it does not have a benzo in your system. Trust me on this one... try hard to stay away from those. Yoga has the same effect and does not cause this kind of worsening of anxiety overtime.
Hang strong man. It gets better. Don't ever give up.