HELP! Chicken Sick and Attacked

[Grace8269]

So, a couple a days ago I noticed that my hen Quinn had laid a yolk. The soft shell was pulled out by myself. Naturally, I thought "calcium deficiency". She also had been losing feathers, even though she wasn't molting. I assumed it was just my other two hens pecking her, and I thought it would get better. However, within a week almost all of her feathers had "bite marks". It was like there was an upside down "V" on each feather. Also, her butt feathers had been gone for about 6 months. Thinking it was "calcium deficiency", I fed her oyster shells and crushed egg shells. Also, about a month ago, I thought Quinn had coccidiosis. I treated her for it, and she got better. But now I am concerned, because she hasn't laid an egg (or yolk), in three days. Quinn is a Rhode Island Red hen, who is about seven pounds. Any advice would help, thanks in advance!

 

[chicken3fly]

So, a couple a days ago I noticed that my hen Quinn had laid a yolk. The soft shell was pulled out by myself. Naturally, I thought "calcium deficiency". She also had been losing feathers, even though she wasn't molting. I assumed it was just my other two hens pecking her, and I thought it would get better. However, within a week almost all of her feathers had "bite marks". It was like there was an upside down "V" on each feather. Also, her butt feathers had been gone for about 6 months. Thinking it was "calcium deficiency", I fed her oyster shells and crushed egg shells. Also, about a month ago, I thought Quinn had coccidiosis. I treated her for it, and she got better. But now I am concerned, because she hasn't laid an egg (or yolk), in three days. Quinn is a Rhode Island Red hen, who is about seven pounds. Any advice would help, thanks in advance!

maybe she is stressed or has an egg stuck in her butt

 

[Gallinarium]

Pictures?