My chicken is sick, need help

[cya]

My chicken is sick. She is weak, can’t hop up to roost at night. Her crown has gone limp. I see her eat and drink, but she is really skinny. Her crop has food, water in it. I isolated her, took her to a vet that gave me a script of cisipride and amoxicillin to help her. I couldn’t get but a little amoxicillin down her, got all cisipride down her. I used a syringe to get water and probiotics, electrolytes down her. I gave her solid feed, cottage cheese, cantaloupe after a couple days. She seemed to be doing better so I put her out with the other chickens a couple days ago. I’ve kept an eye on her and she’s back to looking, acting sick again. There’s a rooster in the coop with my 4 hens. He’s been jumping on her back and dancing around her. I’m scared he and the other chickens will start attacking her, so I don’t know what to do to save her. It cost $200 for the vet last time. I can’t afford it again. Can anyone please advise me?