Someone Please !!!!! Bumps that sometimes looks like they were blisters after th

Tweet

they were scratched.Then they leave a dark spot on the skin that seems to fade away after months. What in the world is it. My friends teenage boy cames home with them everytime he spends a night with his Grandmother. His mother will not make him go to the doctor but I think she should. She sits around worried about what it maight be but doesn't dol anything about it. She asked me to look it up on the computer.. red bumps that itch, when scratched they look like the skin is gone like when you bust a blister,after the bump goes away that spot on the skin turns dark,sometime real dark red,sometimes looks dark gray /blue/black with red in it. I have never seen anything like it before..please help it you think you may know what it is because if i do not come up with something on this computer she will not take him to the doctor. I have tried webmd it did not help.any ideals ??