To the annon. poster asking about ear mites.  I can only tell you what was
told to me by my vet.  Apparently it has been discovered ( although I don't
know when ) that unlike cats and dogs, ear mites in ferrets don't just live
in the ears but can take up residence in other places on the ferrets body
reinfesting the ears.  You might want to try mineral oil ( ask your vet how
much and how often ).  The shot your vet probably wants to give is Ivomec
and this usually takes care of the problem.
[Posted in FML issue 2970]