Hi
I would maybe get some type of4 cram to put on sores se if it works
I would got to the docter could of been a spider
That looks necrotic.
"If the wound is becoming necrotic, it will often begin to turn purple within 24 hours. If the skin does turn purple, it is likely that necrosis is on the way and will then turn black as the cells die."
Id get that taken care of. Necrosis is very, very bad. If you want to see, just type it into google images. Yours is more than enough to warrant seeing a doctor kinda quickly.
where in the world do you live? Austrailia?