Older cat always has dandruff and sensitivity?

Your kitty isn't grooming herself - she's got pain from arthritis! That's why she bites, she's trying to tell you that it hurts when you touch her their. Yes, it's something "old age can bring on" but shame on the vet for not prescribing something to help her out. Go to the pet store, and get her a bottle of Cosequin. It can be very helpful to relieve the pain of arthritis in older kitties.