If it is EYP, you are going to know right quick actually. Her belly will look like its dragging, her legs will be more splayed out to the side... She should have constant poopy feathers on her rear, sometimes looking like yolk/egg white. Her belly will also feel squishy, almost like a how a sour crop would feel, only her belly. If it is EYP, then the antibiotics are clearing the infection, keeping her alive long enough for her to get the infection again, because she is internal laying still. You can keep going with the antibiotics. But if it is EYP, you may be better off culling her.
If it is parasites, You can also get Ivomec pour on... it is for cattle, but, works for both internal and external parasites. I use zimecterin gold horse paste myself, and that has worked very well, Just need a small pea size amount, directly in her mouth. You may want to bring her in, set up a hospital space for a few weeks, and feed her protein rich feed and supplements. You may also want to stop giving her antibiotics until you know for sure she has an infection. You are not doing her any favors by giving her antibiotics for something as simple as worms... IF you can get poop sample to a vet in order to check for parasite, or if you have a kid with a scope to look for worms... some kids do... anyway, if you can afford a vet visit maybe do that...
About the green poop... It is not only a sign of not eating enough, this is also a sign of organ failure, liver damage. Usually when it becomes constant, it is a sign of near death. Not saying that she's going too, but if she's had a severe case of worms, and you don't always visually see the worms in the stool, they have been consuming the food, her body starts to consume itself, just like a starving person... So, since the body isn't getting the nutrients, you can have a chicken pooping green since the food is not going to where it should. Again, a fecal check would be a good idea.
A fecal sample can also tell you if she's got ecoli... In which case, you also have the green poo, weight loss, stop egg laying. It can be a difficult and tricky infection to clear. Again a hospital containment with heat, would probably help....
What kind of hen is she? I have had bad luck with my silver laced wyandottes and EYP... I am culling one in the morning, I had her on antibiotics also, and she is still not getting better. There was some improvement, but tonight she took a turn for the worse, so... culling in the morning and burying her in the chicken cemetery in back...
You did all you could for her.
