Hi, Over the last 3 weeks there has been some discoloration on my right knee. I dont know how it began. I just noticed it one day as at times it feels itchy and when i scratch it becomes flat like dry skin. But only that part not the rest of my knee. I always keep my knees covered and its never exposed to sun. But i am getting worried now since its spreading. It was slightly small initially but now its spread to about 2 inches in diameter. It looks dark purplish n reddish. Can you help me? I have attached a picture. Thanks.