In my experience, the following helped me.
* Meditation
* Deep breathing exercises
* Exercising especially cardio.
* Cold water showers
* Learning about panic attacks
* CBT
But they also know many doctors aren’t able to help much with panic/anxiety, not because they’re ignorant or incompetent but because the causes and effective treatment options vary so much from person to person, and the whole topic is not very well understood by anyone, really.
One of the treatment options suggested above (CBT) is a conventional medical approach.
The others are often reported to be beneficial for some people and are not commonly reported to do any harm, so it is fine for someone to suggest them.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3772979/
Anecdotally it's very helpful to myself.
Deep breathing can be part of CBT too.