Breathing exercises
Guided meditation/hypnosis (via YouTube videos)
Distraction by doing the things you like to occupy your mind with something else
Also, if the panic is very incapacitating (ie, you are in freeze mode) and cannot obtain a prescription - maybe herbal remedies might help?
Sensei wrote a very good guide on these - but as with medications, be careful, some herbals can be very strong and can be influenced by the foods you eat (they can also impact medications, but if you do not have access to medications, this may not be an issue). Here is a link to his guide:
https://sanctioned-suicide.net/threads/a-guide-to-herbs.39433/page-3#post-1252529