Its an infection of the skin and skin cells . If left untreated. it can go into gangreen . Which can lead to amputation . Diabetics deal with this alot because they dont heal well. You get a hot spot with it , It can come from a scratch , bug bite~ especially spiders, anything that lets the right germ in there fester. It also gets into your bloodstream and will spread. Like downward in a leg. Its not pleasant to look at.
*******If your sqeemish dont look further ok *******
I am not one who posts stuff like this. But here is a small section of the cellulitis I had last year. Its red , blistery and hot to the touch ~ feverish. And it was very painful.