i'll leave her in "solitary confinement" for a while away from the other rats and see how she goes. i haven't seen any red discharge from her nose yet. currently i have her sitting in a shoebox on my desk here so i can keep an eye on her, and she seems to be calm and quiet inside the box. every time i go to check on her she starts sniffing at the air and then starts sneezing from all the active sniffing. she hops out, does a quick walk-around and then jumps back in her box and i keep the lid closed so she can rest.
i'll stick her in a bigger container for the night, with her shoebox inside of it in case she wants to do a walk-around.
if she doesn't show signs of improvement, or seems to be getting worse, then i'll cull her and one of my snakeys will be getting a feed.