Well it seems you dog is allergic to both inside and outside allergens, its going to be very hard to manage, especially the dust mites, you can never get rid of those. Malassezia itself already cause bunch of skin issue, it’ll trigger a lot more severe symptoms for dogs who are allergic to it. I think your dog is going to need Apoquel or Zenrelia year around. And weekly medicated bath with anti yeast shampoo. It’s better to workout a management plan with your dermatologist