Did she have a skin scraping done at the vet to confirm? (I know you said you brought her, but didn't mention what tests she had done) If it is in fact demodex mange, than it seems your vet may need to change her medication or dose if it is not working.
Another thought that came to mind is perhaps she is having allergic reaction to something and may need something adjusted (food, environment, etc)
Another thought that came to mind is perhaps she is having allergic reaction to something and may need something adjusted (food, environment, etc)