I am writing this because I did a lot of research to try to figure out what was going on with our little Buckeye. I saw a lot about B12 but never amount given or exact symptoms that were being treated. So here is my experience. I hope this helps someone in their desperate search to diagnose and save one of their flock. Ok, 10 days ago our 3 week old Buckeye got sick, really sick. She was viable smaller the the other chick but up until this point pretty normal. 10 days ago she started sleeping a lot. 8 days ago we noticed the other chicken beating up on her. When we took her out her legs were very weak and she was having trouble standing. We separated her using chicken wire so she could see the other chicks, but could rest and have her own food and water. 7 days ago she could pretty much not walk. She would try and fall over. She lost her appetite so I started her on Nutri-Drench full strength for 1.5 days. I gave her a little with water through a eye dropper every 3 hours. 5 days ago her appetite was back, but she was still very weak and off balance (although she was trying). I was doing research like crazy trying to figure out what was going on. The things that most closely matched her symptoms were Mareks and a vitamin B12 deficiency. We special ordered the Buckeye, so we called the feed store we ordered her through and found out she was vaccinated for Mareks....so I turned my attention to other things. We had all our chicks on starter feed and had vitamin supplements in their water however I was willing to try anything at this point. So 6 days into it we started her on a pure vitamin B complex (liquid) that contained a huge amount of B12. I gave her 0.05ml of B complex 3 times a day for 2 days....and she made almost a full recovery! She could walk without any issues and only way bled a little when she dropped her head down to eat or drink. I went down to 0.05 twice a day doe 2 more days and I am happy to report...she is back to normal! She gets to go back with the other chicks tomorrow. We will continue vitamin B treatments 2x a day for a few ore day (totaling a week) and then I will probably add a drop or two into the water for a few more weeks just to make sure. If you have a chick suffering from the same thing, don't give up! Get them Nutri-Drench and vitamin B12. We were sure this chick wouldn't make it. She was very bad off...and now 10 days later she is recovered, growing her adult feathers, gaining weight daily, and ready to join the rest in the main brooder box. We are thrilled...a little shocked, but thrilled!