Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner, but can you tell me:
Has she been licking the area?
Did you mean it doesn't bother her?
Any swelling in the area of discoloration?
Any changes to the skin here (ie crusting, pimples, etc)?
Can you take a photo of this area? If you can do so and post them online, it will let me see what you are seeing. To post them, you can either use the paperclip on the tool bar. Or if you cannot see that on your phone/computer, then you can post them on any site (ie Flickr, Photobucket, Imgr etc) and paste the web address here for me to have a peek.