I must say it doesn't look very good:(
See if that improves with the antibiotics. I would take a guess she's got something wrong with her reproductive system.
Do you still have that? If you do, can you cut it open?
If she's perked back up, I would put her back with the flock.
I'm not sure what that is. Could be an intact follicle, but it's in an odd shape.
What antibiotic are you giving? I think I would finish the antibiotic treatment and just...