I may or may not have a similar problem....I have 15 Anconas 1 week old. They all seemed great till this morning. A couple started acting funny..........lethargic and then it was like they were having seizures, shaking their heads back and forth. Then another flipped on its back and couldn't get back up. I read it could be a vitamin deficiency or bacterial infection so I added a vitamin electrolyte mix and duramycin to their water. They had been getting vitamins in the water up until yesterday, then I stopped because the hatchery reccommended plain water. I mix my own starter because you can only get medicated chick starter here, and I do add vitamins but maybe not enough. They have also been getting mashed hard boiled egg. I changed the bedding crook wood shavings to newspaper because I was worried they might be eating it and it could be causing problems.
Now it seems like the whole flock is acting lethargic though no more "seizures ". They seem to be drinking a lot but not eating much and some of them are calling a lot. Others are acting pretty weak. Any ideas what I can do? I certainly don't want to lose them all.