I have a 6wk old chicken that is not gaining weight as much as her 7 peers bought at the same time, and who has had progressively worsening issues with balance and standing over the last 2 weeks or so. First she just walked a little more slowly and would sometimes step on her toes, then started often sitting down/back on her heels (upper legs??), and now spends most of the day sitting and sometimes has to flap her wings to keep herself balanced even when sitting. She also keeps her head tucked in much more than the others. I've given her nutri drench for 3 days now, but doesn't seem to be helping. Others aren't picking on her, and seems like she can still access food and water. She can still walk, but doesn't often. Should i separate her? Get her back on electrolytes with vitamin B?