I hate to be the bringer of bed news, but it sounds that your older ferret
has a tumor on one of its adrenal glands.  Symptoms of this are rough and
thinning fur accompanied by baldness starting at the base of the tail...and
lethargy.  I can't comment on the yellowish/orangish patches on body or
blood/scabs on chin and mouth.
 
In any case, you need to get her some medical attention ASAP.  If she gets
too weak she will never survive surgery.  Also, if she gets too weak she may
never recover in order to become strong enough to survive surgery.
Bloodwork can confirm an adrenal tumor.
 
P.S.  I use the words adrenal tumor bacause I am obviously not a vet and
can't recall for sure the proper name,
 
Best Wishes
Michael Landis  [log in to unmask]
Krysta  (I'm with this big lug :0)
[Posted in FML issue 1977]