I had a sporting injury in '92 where I destroyed half of my face. That's not the terrifying illness/disease part. For the months following I had to push puss out of my left tearduct manually. Because my tearduct basically failed on me.
I would have moments where I would wake up in the morning with my eyes glued shut.
Two years following I woke up with the entire area around my left eye freaking huge and bulging out. I screamed in horror. It was a staph infection. The doctors wanted to look at it later, but the fact that it was so close to my brain made my time there pushed up a little faster. Four nurses held me to a table and a doctor came at me with a needle, to the tearduct. You'd be surprised just how many little nerves bundle up in that area, and he did not want to use numbing. Having my arm ripped off by sharks would have been less painful than that needle in my tearduct for 30 seconds, followed by a secondary jab.
After that I pushed blood from my eye for two weeks before getting a second staph infection. Went back to the doctor, to which he said, "Well, guess the needle was kind of pointless then. Let's go to surgery." Where I spent another two weeks in bed puking blood and drinking soup and Mt Dew through a straw.
Still get nightmares about it.
Oh, there was another time more recently. I had a bad cough and my inner ear was cripplingly painful. I went to the doctor, who told me to take two aspirin and call me in the morning. Went back two days later far worse. He took a q-tip, rammed it into the back of my throat, and told me I was fine. Minor Virus, everyone had it. Few days of suffering later, I could not lay down without coughing violently. Then I could not breath. Was rushed to the ER because one of my tonsils took over my throat. Tonsillitis. They shot me with some kind of medicine and drugged me up for a few days and I was right as rain.