It sounds as if you cat may be having another upper respiratory infection (URI) episode since it's not uncommon for shelter or rescued cats to occasionally experience recurrent signs....especially if herpes virus is involved. Similar to humans, this virus can remain in the body and rear its ugly head at times of stress or changes in the household or environment (although sometimes we can't identify a trigger for some patients.
Secondary bacterial infections can develop (the nasal and/or eye discharge can be green or yellowish in color) and when this happens, antibiotics are usually dispensed. But, since the discharge that you're seeing is clear, then it doesn't sound as if a bacterial infection has developed...not yet anyway.
These cats can often run low grade fevers and not feel like eating or drinking so it's good that she still has an appetite.
These episodes typically last anywhere from 10-14 days just to give you an idea of the timeline.
What you can do at home would be to:
1. Use warm water to clean the eyes and nose of any discharge that builds up. Over the counter artificial tears can be used to flush out the eyes.
2. Nasal decongestant drops can sometimes be helpful although many cats don’t like them very much as you can imagine. The medicated ones (a-c below) should only be used forthree days in a row, with one drop in each nostril; otherwise what’s known as a rebound effect may occur. This is one reason why I prefer"d":
a. Pediatric otrivin=0.05% xylometazoline
b. “Little Noses" Decongestant Nose Drops with phenylephrine hydrochloride
c. Oxymetazoline which is the primary ingredient in Afrin or Zicam
d. "Little Noses" Saline Spray/Drops non medicated which can be used more than three days in a row.
3. Use of a humidifier can help to moisten the air.
4. L-lysine can help with any eye issues. Herpes viruses can settle in the eyes and cause low grade issues there. This supplement would be given daily (250 mg). The feline product is available on the internet as either a chewable treat or a paste; the human version comes in a capsule and the contents can be sprinkled on wet food and given this way as another option.
5. Probiotics such as Forti Flora have been shown to help many of these cats with URI's; probiotics aren’t just useful for gastrointestinal issues. This particula rproduct is available as a powder which is sprinkled on the food everyday and can be purchased at many pet/grain stores or online.
As long as she's still eating and the discharge is clear, then I'd wait it out; a vet visit should be necessary.
I hope this helps. Deb