Hello and thanks for posting. Your cat has a classic presentation for flea allergic dermatitis. Even if you are not seeing any fleas, I'd use a few months of frontline or andavtage on her. When using spot on products, be careful to use only products labeled for cat use and stay away from over the counter products that have older generation insecticides.
Another possibility is that Ginger is too old and arthritic, or too plump to easily groom her back area and tail base. You can dampen a paper towel 9like bountry-not the industrial strength ones0 and run it over her back to help pick off the dander and loose hair.
If she has plaques of sores and non healing crusts, it may be that she has a skin infection and while age is not a disease, it mat be that her immune system isn't as strong as it used to be and she is more susceptible to a dermatitis.
I have been brushing Chloe every day. These spots are around her neck and ears also.
Would the wipes with aloe in them help out any?