Just an infection inside one of my fingers. Too deep for clinic surgery, so I was prescribed antibiotics.

But the doctor also had information I hadn't previously known about panic attacks, that also neatly explains a lot of the symptoms I get during them. My panic attacks flood my body with a hormone called cortisol, which, among things, increases metabolism and blood sugar (which lowers my appetite) and suppresses the immune system (which is why I got this opportunistic finger infection). This fits with my anecdotal experience that panic attacks feel more like toxic physical injury. They may be triggered by the amygdala (through whatever mechanism - OCD, PTSD, etc. - that makes them easy to trigger), but from that point, they play out as real physical illnesses. The Wikipedia article on panic attacks says that they are not dangerous and should not cause harm, but it also says that they usually peak after 10 to 20 minutes. But since mine last days - not minutes or hours - I am physically injured, by the sheer amounts of lingering cortisol in my system.

I think it's important that panic attacks never be treated as a kind of misbehavior or overreaction, because the mechanisms that cause them are often fundamentally divorced from logic and reason to begin with. Since panic attacks run in my family, I know that some family members are actually prone to having them with no cause whatsoever (panic disorder). If someone has a panic attack, they shouldn't be treated like they chose to have one, as if they're having a temper tantrum or mean you insult. And I know from personal experience that if someone reacts negatively to me because I have a panic attack, it only makes it worse and can even create new social panic triggers. I mean, considering we're supposed to use our logic and reason to help us be better-adapted social creatures, it's really annoying (to me most of all) how irrelevant logic and reason become during panic attacks or in managing existing panic triggers.