Hi,
Most humane societies will take sick cats, but would likely euthanize her. However, that may be the most humane option for her if she's as bad as it sounds. She could have a number of different things wrong with her. One of the feline viruses: leukemia, FIV or FIP seem fairly likely because she's an outdoor stray cat. Here are links to pages about these diseases if you want more info:
http://www.vet.cornell.edu/fhc/brochures/felv.html
http://www.vet.cornell.edu/fhc/brochures/fiv.html
http://www.vet.cornell.edu/fhc/brochures/fip.html
Lung infections, severe respiratory infections and heart failure could also cause these symptoms. If you don't have the money to take her to a vet, I think your local humane society is your best bet so the kitty doesn't suffer.
If you have further questions let me now. If this answers your question please click accept.
Thank you.
Lynn
Veterinary Assistant
worked at a vet clinic for 15 yrs, BA in biology, have had cats most of my life
Thank you Lynn.
A
You're welcome.