Hi. I'm Dr. Lee and will do my best to help.
The dark spots will remain there forever. The dark spots are hyperpigmentation, a normal darkening of the skin after skin infections or skin diseases. The pigment melanin inside the skin produces these pigments after being inflamed (skin inflammation, dermatitis), creating this dark spots/skin. There is nothing you can do to get rid of it. All you have to do is to keep her comfortable and itch free by using steroid. You can also ask your vet for a medication called Atopica, which helps a lot with environmental allergies, though it is an expensive drug.
Please let me know if you have any questions or concerns. Thank.s
Malassezia is an yeast infection, and it is secondary to other problems, such as allergy. Yeast infection is not the primary problem. Infection can be present, either yeast or bacteria. It is best to get her to your vet for exam, and skin cytology, to determine what infection that is, so the proper medication can be prescribed. There can also be skin parasites, or fungal skin infection. The botXXXXX XXXXXne is that, she should go see your vet for a check up.
Please let me know if you have any questions or concerns. Thanks.