One of my hens, Florentine, died - she had the same symptoms. I isolated her and kept her clean and gave her vitamins and feed and yogurt with egg yolks, and some Braggs ACV in her water about once a week. Finally, she could not stand at all and laid on her side..she got weaker and weaker and one day I couldn't stand seeing her suffer any more, so I took her to the vet and had her put down. It almost killed me, but the nurses and the vets were so sensitive to what I was feeling...they sedated her a little, then when she was calm and sleeping, they put her down, then brought her out to me so I could take her home and bury her. I can tell you it was a very painful experience for me...I thought she had fallen from the roost and injured herself because she was on the floor of the henhouse one morning when I went to let all the birds out. I couldn't feel any lumps or bones sticking out, and she never acted like she felt pain when I picked her up. I took her out and just held her in the crook of my arm when raking the pen, but she was not even interested in visiting her friends. I knew it was time, so I had mercy on her...hurts.
The price of love is often grief and I know how hard it is to make a decision to put down one of your birds. Sometimes you have to.
