That pic doesn't come close to doing it justice.
It's a bacterial infection in the skin.
Sunday at 4pm I started getting cold, so I went and laid down in my bed. Got worse. My wife got me some Motrin and Tylenol for the fever that started. I was laying in bed, fully clothed, wearing slippers over my socks on my feet, under two quilts. I was shaking violently and uncontrollably for an hour. That finally stopped and I got up to vomit. Side note: orange juice tastes the same coming up as it does going down, as does Nyquil. About 8 o clock I started noticing a pain in my groin muscle, literally right next to my manhood. Kind of felt like I'd been kicked or hit by a ball. I was able to sleep until 4 am when I woke up to pee, but I was shaking so bad again I almost pissed all over the bathroom. Took more Tylenol and Motrin. Slept until about 7:30. Got up and noticed the pain had spread all the way down my groin muscle to my knee. I'd sprained my ankle Thursday evening, so I attributed the pain to walking funny because of this. Monday was spent controlling the fevers that spiked every 6 hours or so. The violent shaking type. No more vomit (probably because the only thing I'd eaten was a piece of toast), but constant nausea. Woke up Tuesday morning and the pain had gone to my shin and then across it. Then the redness, swelling, heat, and blister looking things started popping up. I showed them to wife who instantly freaked out. We took some pics and sent them to a nurse friend who said I needed to go to an InstaCare or ER immediately, because I probably had cellulitis. I was so dehydrated that my urine was so dark I thought it was bloody. But the doc said it was likely dehydration.
Now I'm on three rounds of IV antibiotic, two oral antibiotics, and an anti nausea pill. The leg looks and feels worse today than it did yesterday, but they said that was going to happen. Overall, I feel better today than I did yesterday. My nausea pills are supposed to last 6 hours, but I'm only getting about 4 1/2 out of them. They said if I'd waited too much longer to get looked at, I'd likely be hospitalized.
Oh, and now that I've had it once, I'm much more susceptible to getting it again. Awesome. I think I'll start dumping a gallon of alcohol on every cut I get from now on.
tl;dnr
This sucks donkey balls. Hope and pray you never get it. Wash all cuts/scrapes/lesions/wounds immediately.