Look up shingles.
I had a mild case of shingles. Boy, that was not fun.
Mine was in an eye.
Being vaccinated against chickenpox does not protect you from shingles in adulthood. There is a risk of developing shingles from having been vaccinated, it’s a live virus vaccine. I’ve had chickenpox as a child, and I’ve had shingles as an adult, it’ll be ten years ago come Christmas Day. It started out as two small bumps behind the hairline on my left temple, they felt oddly cold, no real pain but sort of uncomfortable. That progressed in a few hours to being quite painful and starting to swell a bit, I became concerned that I’d been bitten by a spider in my sleep, it really was an odd sensation, cold, hot, numbness, pain, all rolled together. Difficult to explain. By the end of the day it had developed into a rash that spread onto my forehead on the left side, by the next morning it was in my left eyebrow. Finally went to a doc in the box, they prescribed several things, hydrocodone for pain, gabapentin and Neurontin. One or the other of those really knocked me for a loop, couldn’t drive a car, really out of it. Wasn’t the hydrocodone, that alone just helped with pain, didn’t feel buzzed or out of it. So it was one of the two for nerve inflammation and damage. Can’t begin to describe the pain, it seemed impossible for a mere rash to hurt like that, it honestly felt like it was drilling down into my skull and into my brain, very intense. I still have numbness in my left eyebrow and a fading area that only showed when I had something of a tan, slightly depigmented I guess. I wouldn’t want to ever go through that again. It was truly debilitating and took a good week to get to the point that I could function again.