When I panic, it feels like my heart is stopping, or that my guts have been turned inside out, or that some sort of massive steam shovel or something has pulled out all my insides and rearranged them and dumped them into random places in my body. Sometimes I feel like the walls are falling in on me, and I can feel the space I am in (or at least my perception of it) going dark. Sometimes I start self-harming by punching myself or slapping myself or punching walls or hard objects or hitting my head against them. Sometimes I become dissociative and do not remember the incident. Sometimes none of these things happen and it manifests quite differently.