Thanks for all of the advice! I will do a necropsy when I get home and post results.
She was under a year old, i got all of my chickens back in late April, early may.
I have a Rhode island red that hadn't been doing too well the past 3 days, and she just passed this morning. She was favoring a leg so she was brought inside to check on it, and then died 3 days later. No issue with leg, not broken or anything, she was just extremely lethargic and underweight...