I think a vet visit is needed for a good check-up. I have seen this
behaviour when a ferret was suffering from either pain or discomfort
due to some unseen (to owners) medical problem. Explain to the vet
that the changes are such that you suspect an underlying problem is
disturbing the ferret.
Tony (not a vet), Sugar and Suki.
In memory of Sally and Sue.
[Posted in FML 6209]