Yeah, man. This happened to me as well when I was younger. I learned to control/stop the panic attacks in a little under a month of having them though, but ugh, that shit sucked. It's all in your mind though. I got so high off that shit that I was actually seeing things, had heightened senses, horrible anxiety, had random images running through my mental eye whenever I closed my eyes, felt like my heart was going to explode, etc. That shit SUCKED. I can't even smoke weed. Forget psychedelics, I'd probably lose my mind. Oh, and I tried watching The Evil Dead 2 while in said state and also attempted to listen to Goratory...that worked out well as you'd imagine!
How people get fucking high off their ass and play in grindcore bands is beyond me. I don't know how Cephalic Carnage does it.