Thanks to Jodiej for the informative answer.
HV
I have a solution for you. I think that your problem is hemosiderin staining--your skin has been stained by your blood. I had the same problem from a black eye I got from having eye surgery. Try googling "hemosiderin staining candela laser" to locate a small study showing that an AlexTriVantage laser can remove this type of discoloration. I used the doctor locator feature on the website to find a dermatologist in my area. The laser treatment wasn't painful or even very expensive. The discolored skin turned black after the treatment and flaked off after a few days. BTW, this is the same laser used to remove tattoos.