One of my 3-4 month old marans has been sick for several weeks. She is very lethargic, always stoops with her eyes closed, seems to have a hard time balancing, and doesn't really move. I can't see anything wrong with her. Vent, poop, legs, bones, stomach, eyes, nose, all seemingly ok. She used to eat and drink, but now just sits in a box. Her poop has become clear and viscous, and I have to force feed her. For the past week I have had her isolated in the garage and have been force feeding her water with durvet, and I see no improvement. She doesn't seem to be in pain, but she can't be very happy. If i knew she was going to get better, I'd be happy to continue what I'm doing. But I don't want her to suffer needlessly. Any advice would be great. Is it time to cull?