I have a "soft spot for the underdogs" too- I think that's why I love snakes in the first place. They get such a bad rap most of the time.
When you soak a snake for mites, only use a drop or two of dish soap- that's ALL you need to break the surface tension of the water so the nasty mites drown, instead of swimming or floating.
From that picture, the spots all seem to align with her spine- is that what you're seeing too? I wonder if something in her previous housing was irritating to her skin? I hope she'll be okay, but if they increase or don't fade, it would be a good idea to see a vet. I agree though, I'd check her appetite first.