Unknown chicken behavior?

[Missconduct010]

I'm sorry I don't really know how to title this without going into a novel.
First I am somewhat knew to pet chickens and have been Lurking on this site for quite some time.....it's wonderfully helpful!!! So thank u all!!!
Ok
So we have three Long Island reds. All about a year and a half old.
About a month ago one of the girls started getting picked on by the other two. They pecked her cone up and she had alittle feather loss around her head. She was terrified in the pen so we put our Xlarge dog cage inside, and would rotate seperating them. I didn't want to just isolate the one being bullied and make it worse for her. So We did that for around 2 wks. We then changed the inside of their pen, started letting them out more often and interduced some new "toys".
It's helped alittle. I have not noticed her being pecked, or being attacked. But she still has feather loss around her head, I'm hoping it's just taking some time for the feathers to come back. She started hanging around them alittle more, but will still have a fit if they get too close. I believ her behavior of being flipped out and nervous, IS making her a target.
BUT.....
About 2 weeks ago we noticed that the bullied girl (tater) was spending all her time in the coop. While the other two (the Bully-ers) refused to go into the coop at all, they are even spending the night outside on top of that dog cage. The bully-ers won't go into the nesting boxes to lay, and prefer to lay in random spots in the yard? When tater started isolating to the coop she also started to be "puffed up" while in there. When we try to touch her she seems to like "growl" as if to say back off.
When she started this we took her to an avian vet who gave us an antibiotic and wormer. Nether has helped this behavior. She's also only all poofed up while in the coop.
We let the girls out to roam everyday, and she'll only come out if we physically take her out. She will come out, scratch, take a "bath" then go right back into the coop. If the other girls get to close she looses it and runs away, they will chase her but don't peck at her anymore.
My concern is why the Other two refuse to go in the coop with her?
She eats fine, is still laying (even though she did lay a few of those "jelly eggs" when it first started) but not laying everyday or like she was before all this started.
I'm at a loss here. I hope I included all the details here so I'm sorry for the length. I don't know what might be going on, and if there's anything else I should be doing. The free roam around 4 hours a day, have access to the diamatis earth for dusting and are constantly getting treats of fruit and worms! Any thoughts on this??? Why would the other two refuse to go into the coop? Ok I'm done, sorry!
Thanks for reading!!

 

[RoostersAreAwesome]

It looks like she might be broody. Does she have a spot with no feathers on her chest? Is she sitting on eggs? If you put an egg by her, does she use her beak to put it under her?

 

[Missconduct010]

Holy smokes! I think you've got it!!
Is she always on eggs? Yep
Does she move eggs under her? Yep
Doesn't she constantly return to her nesting box? Yep
No feathers from her breast missing, but after some googling it really does seem like she is.
Poor girl wants to be a momma....awe!!! Unfortunately we are not in a rooster friendly so being a momma isn't possible.
When we let them roam around, I have recently been closing the coop so she can't run back inside. I will start to close off the boxes as well.
Thank you SO much!! I was so worried about bullying/illness I overlooked the obvious.
Where's the face palm emoji? Lol

 

[Kiki]

LOL.

Try putting Miss Broody in a wire bottom cage, slightly raised of the ground with NO bedding material in it.
Leave her in this cage with water and feed for a few days.

 

[Kiki]

Can I ask...
What kind of antibiotics and wormer did you vet give? The names?

And did her give you a reason for giving these two meds?