@Wyorp Rock @Eggcessive @Kiki - I hope it's okay that I update you on the situation via this thread post - you have all been so helpful - thank you.
In four days, the situation has not really changed. I have all chickens on Corid drench, and Safguard (individual doses) - they all look amazing and are doing fine from their molt. As for my one hen with the described issues, I did the stated + started Monistat for possible Sour Crop. I "force" feed her water/Corid drench, as well as bits of chicken or tuna, mushy feed and/or treats - anything to get something in her. She barely takes anything on her own. Her poop is still white with green bits and there is very little of it. As @wyorp suggested I have put her back in the coop to be with her mates except when I take her out to feed/medicate her. I don't have a good feeling about this. So now I'm asking - how long do I do this for - I should have seen some improvement by now, right? If it comes to this, I'm going to have to ask my husband to take care of putting her down - I just personally cannot, even though I know it may be the right thing to do. As she sits on my lap while I type this, I know that these things - and the responsibilities - are all part of chicken keeping but this is my first hen that I've had fall ill and I was really hoping I'd be able to help her get through this ...
Part of being a good pet owner is realizing if they're suffering and what you can do for it. If she hasn't laid in months, something's going on.
You either need a vet visit to find the problem, or you need to cull her. I agree with Kiki - how long can you watch her suffer?