ugh anxiety and stress are the worst. I am so sorry you are having to go through this. I was diagnosed with PTSD just this past winter after leaving an abusive marriage. Debilitating panic attacks/nervous breakdowns plagued me for months and come to find out this is quite damaging to your brain and body the more you experience it. Their are some good resources out there but it is just a matter of finding them. You are correct in saying that you somehow learned this behavior and unfortunately our mind and body now uses that response in order to protect itself or warn us. You can train your mind to respond differently. I just started EMDR and a few people I know are going through this as well. It retrains the way you respond to a stressor.
http://www.emdr-therapy.com/emdr.html
There is also neurofeedback which is another method that remaps the way your brain responds to a stressor.
http://www.eeginfo.com/what-is-neurofeedback.htm
I hope these resources help. The EMDR and Neurofeedback have both helped the people that I know that have gone through the treatment.
I truly hope things get better for you and that you can get at the root of the anxiety.

