Has she been eating well up until today? Is she drinking? Are you able to bring her inside to somewhere warm and check her over a bit more and weigh her etc? Do you have a vet or are you hoping to treat her yourself? If yourself, you should probably start researching how to tube fluids and crop feed. You'll need to try to find out what's wrong with her but in the meantime, she'll only have a chance if you make sure to keep her hydrated.
I'd be contacting the people you bought her from if I were you. Maybe they can help? Sept 25 isn't that long ago. What was her condition when you got her? Did you see the setup where she came from? Do you have other peafowl and, if so, did they come from the same place?
Sorry I'm not much help as I'm still learning as well but maybe more details will help some of the experts on here to help you.