Hi there. My honest suggestion would be to talk to a Dr about this, especially when it comes to children. If your son is scratching there and there is in fact a change in coloration of skin, that will be your best bet. Also, if you believe this started after your son started any medications, supplements , etc, then you can always speak to a pharmacist as well. And yes, this does sound like skin irritation, or even an infection. I hope you were able to find the answers you needed. *J*