If she had mites in her ear as you suspect, she would be shaking her head and scratching her ear. Hence the scab you observed. Use an eyedropper to put a few drops of olive oil or vegetable oil in her ears to smother mites, dust wont work.
GRAPHIC PICS
See figure 197 for a photo of wet fowl pox...
Gapeworm are rare in chickens, most likely you're dealing with a respiratory disease. Covey Rise Plantation is the expert when it comes to gapeworms, here's a link. Read posts #13 & #14:
https://www.backyardchickens.com/t/602699/worming-chickens/10#post_7931055