Do you have a picture of her?
The pebbles are probably from her gizzard. Chickens eat small pebbles or grit if it supplied to help grind up their food.
Is she able to stand or hold her head up?
Were you able to get her any vitamins or electrolytes?
Does her crop feel full or empty?
You may have to start tube feeding her:
https://www.backyardchickens.com/t/805728/go-team-tube-feeding
The pebbles are probably from her gizzard. Chickens eat small pebbles or grit if it supplied to help grind up their food.
Is she able to stand or hold her head up?
Were you able to get her any vitamins or electrolytes?
Does her crop feel full or empty?
You may have to start tube feeding her:
https://www.backyardchickens.com/t/805728/go-team-tube-feeding