This is definitely a case to take to the vet. Paper towels are a good choice of substrate to help you monitor, and you definitely want to go for the low side of humidity right now. If you see her soaking, I'd reduce the size of the water bowl so it's not big enough for her to get in. And as I'm sure you know, keep her away from the others. I'm sorry to hear she's in such rough shape, but congrats on your new addition anyhow!