Here are two things I suspect the next step needs to include:
 
Blood tests: CBC with Chem Panel (which includes checking her glucose
levels to see if there may be insulinoma)
 
Xray: chest to see how her lungs and heart look (possible secondary
pneumonia, possible cardiomyopathy)
 
I am not saying that those things are definitely going on, but that with
what you describe it is important to see if one or more is and to treat
accordingly (approaches and info are in the links below).
 
If your vets don't know ferrets then you need to either find someone
ferret knowledgeable or go further than many clients:  more like what
we used to have to do in the past when we had to find info, get
permission to copy it, and then share it with our vets.  In recent
years more vets know ferrets, but it used to be absolutely essential
to find a vet who was willing to learn, seek out information and
after getting authors' permission then print it out for the vet and
to okay extra consultations.
 
Here are some great places to stat looking things up (the ones with
** are by vets and the ones with * contain some content from vets):
 
*  [log in to unmask]" target="_blank">http:[log in to unmask] (very easily searched and used
   health archives)
** http://www.afip.org/ferrets/index.html
** http://home.att.net/~hhoefer/
** http://www.lbah.com/Ferrets/ferret_diseases.htm
** http://www.petcarevabeach.com/ferretservices.html
** http://www.bradleyhills.com/ferret (alternate
          http://www.ferretdoctor.com/ferret )
** http://www.veterinarypartner.com/
*  http://www.miamiferret.org/fhc (alternate http://www.ferrethealth.info)
Collections of links to important health sites:
http://www.ferretcongress.org (in the Crit Refs in the menu to your
left, just click it open; lots of links on many health and legal
aspects)
http://www.trifl.org/medical.html (sorted by disease)
http://www.ferretcentral.org  (great basics, links, many languages)
http://www.fothferrets.com/ferretinfo.html
 
BTW, I am going to mention something now that is not readily obvious to
anyone unless the person has had ferrets for a good while.  Reading up
on health problems is best done before ferrets are sick; that way if an
emergency occurs the person knows in what directions to jump and how high
to jump because the knowledge of the health problems themselves is what
is feeding the orders to you.  I strongly recommend that everyone read
diligently in the above resources and more as soon as adding the first
ferrets to the family, if not before.  That is something pretty much any
person would NOT think of automatically so it is worth a mention.
 
---
 
IBD: with IBD it is common for one approach to work for a while and
then later a new one need to be tried.  Some cases respond to Pred
(with Prednisolone sometimes having a better shot than Prednisone
perhaps because the GI inflammation can secondarily can inflame the
liver and the pancreas and Prednisolone skips a liver processing step
which Prednisone has), some respond to other steroids, some respond
to a combo of steroids and antibiotics, some seem to respond to
nucleotides, a number respond well to eliminating certain foods with
chicken or poultry in general being common problems and for them a
hypoallergenic prescription food makes sense.  A truly extreme case
was Rinky Dink's and you can read about Rinky Dink in the FML Archives
(See URL in the header of any day's FML.) or the FHL Archives (See above
link at sonic-weasel.)
 
It is too bad those GI samples weren't taken in case there is an
Eosinophyllic problem.
---
 
I am not a vet.
Sukie
[Posted in FML issue 4308]