Hi welcome to Health care magic forum.
Thanks for calling.
It appears that the injury must be a crush injury
that is why the doctor didn't prefer to give stitches, And the healing is with extensive scar. and sensory loss.
If you have diabetis you should be cautious, and must controle the sugar promptly, and through out the course of treatment.
You may have to use high potency bcomplex and anti oxidants for tissue repair. if the black skin is the scar tissue, we cant help to have a normal skin there.
Wishing for a quick and healthy recovery .