Time to have a vet do a urinalysis and a CBC with Chemistry Panel!  Some
ferrets just are stinkier, but sometimes there is a medical problem, so
the vet will need to check.
 
If you don't have a ferret-knowledgeable vet go to
http://www.ferretcongress.org and click on the crit refs listing on
your left.  Then scroll down that to the links of ferret vets people
have sent to those links.  If you you are in central NJ we use Joe
Martins of Bellemead Animal Hospital 1-908-874-4447, 872 Rt. 206.
 
There is info on the Pretty Bird food and an assortment of other foods
in archives, both
http://listserv.cuny.edu/archives/ferret-search.html
and
http://fhl.sonic-weasel.org
[Posted in FML issue 4362]