Hi everyone. Thought I'd post a quick update for those who are interested ...
Our little black kitten is doing well. She is now very friendly and full of spirit. Since she is doing so well (we were expecting her to go downhill, not up!) we are going to run some bloodwork later this week. We had expected to be offering Palliative Care to a sick and dying cat but she has been slowly getting better.
The antibiotics she was receiving cleared up her snotty nose quite nicely and she is beginning to show signs of growth (which is contrary to her status previously). She is still not eating as much as she was when she first arrived, but since she has been off the antibiotics, her eating has increased a lot and she is growing.
She is still quarantined and will remain so. I am still hoping the vet misdiagnosed ... but I don't want to get my hopes up. Will know more after the bloodwork is complete.