When I started going through puberty, a switch flipped in my brain, and almost overnight I started exhibiting symptoms of dermatillomania, AKA compulsive skin picking. It's really impossible to explain what a torment this disorder can be. If I knew I had any part of my skin that was raised, blemished, imperfect, I HAD to pick, worry, scrape, whatever it took until the rough feeling went away (though only temporarily, it only felt smooth because there wasn't skin left, but the next day it would scab over and be worse than before). Compound this with being a young teen, who are generally not known for great skin, and things got bad FAST. I remember looking in the mirror, in tears, my face just like a minefield of bloody holes, wondering why I couldn't be normal. My parents knew it was a mental illness, but they'd still yell at me every time I developed a new spot to pick at, which was crushing - I certainly didn't want to do it! I'd stop thinking about it for a minute or two, and then I'd notice, too late, that my hands were covered in blood. It was horrible.
I'm the luckiest motherfucker on earth because I'm pale as the driven snow, and when I scar, I scar white. You'd probably never know what I looked like in my bad days, because until I point out my scars, people honestly can't notice them. People have honestly told me that I always have perfect skin and that they're envious which makes me want to laugh and laugh.
These days, I still suffer from dermatillomania, but to a much lesser extent - for example, right now I'm aware of two small (smaller than a pencil eraser) wounds on my body right now, and I've been covering them with aquaphor, since the texture stops me from picking at them on autopilot. Still, it's a hell of a thing, and I beg you to have sympathy for the poor motherfuckers who look like I did, or didn't get away with such light scars. And parents, for the love of god, raise your children to have empathy. I'm sure you can imagine that middle school and high school were hellish for me, and I still have huge issues believing that guys are interested in me/not just pulling a prank, thanks to the efforts of some grade A assholes back when I was a bleeding, picking mess.
TL;DR: brains suck, and when they start running on bad chemicals, your body can go fucky on itself real fast.