Okay. Well if it's not specifically connected to the powers, he probably could heal it. I will leave it up to you to decide whether or not you OOCly want him to. Since I don't know the canon, it's hard for me to put an interpretation on how the rash is portrayed, so I am content to go with yours - if you say it can be healed separately from removing the powers, then I am happy for him to do it for her.