Hiya, I don't have too much experience with clawed frogs yet, but I've read up a LOT on illness and things to look out for. A rash-type skin problem is a red flag for a bacterial infection. I cant identify it from the picture, but from your description it sounds like it could possibly be in the early stages. If it doesn't look to be clearing up and you can't rule this out, I would be tempted to treat her for this, as it's best caught early.

Hope she gets well soon