Hi thanks I live in Canada so we don't have the same feed. They are eight weeks old. Only one out of four is acting sick there was another one but she seems to be doing ok. This one was the smallest one. My husband got chicken layer instead of chicken finisher and we where feeding that to them for about two weeks when the fowl food finished. The first thing i noticed was her tail started hanging low then she couldn't walk for long distance. We switched the food to a fowl food but it had 20 percent protein so went to the chicken finisher which has 17 percent protein. We also put them in with our year old ducks. At about the same time. I don't think we have any drakes. The three all lay eggs. I also started we call her runty on polyvisol a few drops everyday and the plain niacin in their water.runty has been unwell for about five days now and we have been trying to treat her for the last two. Runty is by herself in the garage with straw and food and water close by she does stand and walk a bit but is very weak. We put her in water three times a day. Her belly is wet we dry it off. We had a heat lamp but it got too warm so that is off now. I also syringes some electrolytes down her two days in a row. Then I gave her yogart with honey last night hoping to get her gut back to normal. She does eat. I put one crushed tab of brewers yeast in her food. We let her see her friends and she quakes loudly and they respond to her. So if there is more i can do let me know. Her feathers look good. She seems alert when she is not resting cackles when we go to see her. The other thing is my daughter sprayed some paint on them so we can tell them apart I wonder if she got poisoned from that. The others are fine.
Don't over do on honey it can also cause low blood sugar the same as sugar can if she isn't eating enough to counter the amount of sugars in her blood stream. You might also want to think she could have been born with a heart condition that is just now showing up as she is growing, hopefully this is not the case but you have to be prepared if she did continue to go down hill. what made me think of that was the breathing you have seen. If you could bring in one of her flock mates to stay with her might perk her up too, they really don't do well in isolation. Just keep up what you are doing and hopefully you'll begin to see improvement soon.
Yes we tried frozen peas in her swim last night and she ate some of them. My husband also has given her two minnows for two days and she seemed to love those too. She breaths a bit fast when she exerts herself. Otherwise her breath sounds are normal. Her eyes are clear lean. She ties to prune herself but is weak so not able to do a good job