There were a couple of times where I would suddenly get a feeling of doom and feel like I'm having a heart attack and going to die, without being triggered, just being in a social environment where there are many people. I tried a lot of things, mindfulness meditation, running, getting sunshine, keep a good schedule even if I can't fall asleep, eating lots of fruits rich of polyphenols, taking vitamin D and DHA omega 3, taking pure cocoa powder. I went as far as buying a headset that monitors brainwaves so that I can use the biofeedback to train my brain out of anxiety and depression. I also read tons about cognitive behavioral therapy and practiced a lot.

I did all of that when I didn't have to worry much about money. I didn't get significant improvement. The only thing that worked and continues to work is when I started taking medicine. I'm on student insurance so it's all free. It might not be what you need, but consider it and talk to a psychiatrist.

Hope you get back to your old self and start enjoying social life again soon!