Ditto nursegirl. When I had a horrible reaction to Paxil that left me emotionally devastated I had stopped working outside the home to pursue my dream of writing fiction full time. Had I still had my very busy job of managing health food stores it might have taken some of the pressure off, but I didn't. Don't quit a job you like because of anxiety; that's great advice because empty time isn't going to repair anything. Nursegirl is wise; listen to the nursegirl.
Ditto Paxiled's post.
You need to seek out some therapy to help you move beyond these thoughts of whatever is haunting you from the past. Worrying about things in the past really is futile, the best thing you can do is learn from your mistakes and move on. You're clearly having trouble doing that, so I think talking to a professional is the way to go.
That being said, the very WORST thing you could do is quit your job. Idle time is the devil for anxiety, it's always best to TRY to maintain the most normal every day routine. If you start dropping out of life, your anxiety and panic will only get worse.
If you decide that you want to try medications to help treat the symptoms, just remember that they take time, usually about 4-6 weeks, before obvious changes are noticeable. Also, therapy is still a must, THAT'S the most vital part of an anxiety treatment plan. Medications won't cure anxiety, but they CAN help to manage symptoms. Yours sound pretty severe and pretty frequent, so I don't think trying the medications is a bad idea.
Obviously, it goes without saying that if you feel you are suicidal, you must seek help for yourself immediately. Suicide is never the answer. I understand being in that dark place, feeling hopeless, but again, it's not the answer. You CAN learn to manage this.
Best to you, keep us updated!
If you know the underlying cause is whatever happened in the past I'd recommend therapy if you haven't exhausted that option rather than medication, though I'd keep it in mind if you really need it. Most of us on this board have no idea why we feel anxious, but you seem to know, and that makes you more amenable to therapy.