Ah, Liz. Just seeing this. Sounds like the vets are taking good measures to get her stabilized, and I like that they're being proactive with the treatments. With the weight she's lost, and her lethargy, they're right to treat for both fungal and bacterial issues. They're aware time is of the essence and they're acting accordingly.
I know the heartache you went through before, and I'm hoping and praying that you are not going through it again. As others have said, those symptoms could be for any number of illnesses. It's not necessarily Polyoma.
Sending hugs and positive thoughts your way, and I'll be keeping an eye on this thread for any updates.