meditation is good, above all patience and trust. It will get better, especially if you are doing NB. But it is going to take some time. I can say I was there too with the constant fear and fight/flight, but months of zinc, calc/mag, meditation, and rest of protocol has helped me about 90%.
I guess what it came down to for me was acceptance and trust. If I accept that my body is a mess, and I cant control it, but that my fears aren't real is was easier to deal with. Then I had to learn to trust my protocol to help me. The last thing that occasionally helped was to challenge my fears/anxieties I guess, like if I was nervous about something I would try to do it, and it would go fine so that proved to me my fears were irrational. There's no easy fix, I hope this helps, just stick with NB and do the best you can - you will get better.