Thanks everyone.
Just got back from the vet. As expected, no obvious signs of illness other than weight loss and odd poops. Teeth fine, blood glucose fine. Need to drop off a urine sample later.
I'm just very worried now what is going to come back in the poop tests. I'm fairly certain there's SOMETHING there given the appearance of her poops. But everything I've read so far just sounds awful and untreatable. :'(