Have you tried testing for scabies? Summerlin kept itching and I thought she had dry skin, but I kept changing her food, started on missing link, changed shampoos, oatmeal baths, everything I could think of and that was suggested. Finally took her to the vet and they said she had scabies, that she had probably had them when I got her a month ago. Now she has to be dipped in some foul smelling medication once a week for four weeks, but she has had one treatment and already looks a hundred times better. Her skin is looking great.
She smelled horrible for the first day and a half, but after that the smell kind of wore off. The only really bad thing is that I can't bath her after she is dipped....