Chicken cannot use leg and blood in stool

[Ducksandchickens1770]

Hi there! My year and a half old Plymouth came out for snack three days ago and was hopping on one leg. The leg she couldn’t use was shaking and curled up. No sign of injury and no heat. She is eating and drinking great. Today with no improvement I noticed some blood in stool and her face more red than usual. The rest of our flock are doing great! Any advice and what could be happening? Never had this before

 

[Wyorp Rock]

Welcome To BYC

Can you post some photos of your hen and her poop?

Has she laid an egg recently?
Inspect her vent to see if there's any evidence of prolapse or injury to the tissue of the vent.
Feel the leg for any swelling or tenderness, any green coloring of the skin that would indicate bruising.

If she's having trouble getting about, you may want to cage her within the run with her own food water so she's not struggling or competing for food.