My latest bout of anxiety (and my most severe) started with my right arm just deciding to go a little numb one day and spasm a little. I waited for a few days (cause I told my wife I wouldn't freak out about anything unless it bothered my for three straight days), and then saw my doctor when it kept happening. He eventually referred me to an orthopedist. While I was waiting for that appointment, I had a big anxiety attack cause I was sure that my whole nervous system was out of whack. When I finally saw the orthopedist, he said that my ulnar nerve (the big tendon-like thing on the bottom of my elbow) was popping out of its tunnel, and it was likely swollen. He gave me anti-inflammatory pills which I took for three weeks, and I don't feel the nerve pangs anymore.
Long story short, the anxiety attack (which I'm still trying to shake the effects of as we speak) may never have been as severe if I hadn't freaked out so much about my initial symptoms. I'm not saying it's the same thing that you have, but it's always been my MO to assume the worst, and that assumption definitely worsened my predicament.
Hi. I get that, but in my left arm :/ Not really sure what it comes from (maybe stress) but it def. gets my anxiety up when it happens. I hope you feel better soon.