my 7 and a half year old brindle boxer holly was diagnosed several years ago with seasonal alopecia,as usual this year its back and as previous years is slightly worse then the year before,but just after christmas she started getting small patches of thick dandruff ,the hair falls out of these patches and her skin on these bald patches has become black the vet didnt seem worried but its still happening and she has several of these patches on the tops of her front legs on her side and one on her back now,plus her usual alopecia,has any one got any ideas of how i can help her please.thankyou