This kind of reminds me of myself. What I do when this happens to me is I ask myself 'what am I afraid of?'

It doesn't always help but I find that often I am making myself believe there is danger when there really is no danger at all. If I can convince myself that it's all in my imagination then it really helps me calm down. I had to make it a habit to face my fears and then actively notice when I came out alive. The more I did the things I was afraid of and the more that nothing went wrong I eventually was able to trust myself and I was not as afraid anymore. Although I still struggle with the same fears they are much more manageable now.

For some reason your brain automatically perceives danger, try your best to challenge your brain and yourself. Start asking yourself regularly, 'what dangers am I expecting?' 'where could danger come from?' 'is my fear realistic or imaginary?' and so on...

All the best to you in your struggle

- A