I'm glad to hear Dollar is getting better and bigger!
As far as ear mites are concerned, I don't know. I did some research and there is a lot more on that page about them if you're interested.
HOW DID MY PET GET EAR MITES?
Ear mites readily transmit from host to host by physical contact. Ear mites came from some other animal with whom your pet has been socializing. Because mites are easily transmissible by physical contact, treatment for mites often must include all household pets.
http://www.marvistavet.com/html/body_ear_mites.html