What Causes Orange And Brown Spots On Knuckle With Numb Finger?

Hello, I have weird orange/brown stain spot on my right pinky knuckle. One morning woke up and it was there. Won t come off with anything. My pinky goes numb randomly also. I don t smoke, tan, garden or anything like that... What could be the problem and when and if i need to take the next when should I do so..