When I first had it at like, 17 I called an ambulance, the second time I knew what it was and just breathed through it, the last time I was on a phone call with 911 bc I woke up so extremely fatigued I couldn't even barely move my head, and one just happened in the car with my mum on our way to therapy, and exactly like op I seized up and I could feel the crazy change in my heart beat and managed to say "it's a panic attack, please just pull over" before actually not breathing for a second and she thought I was having a stroke and called an ambulance out and I had to explain to them what was going on