Previously healthy Guinea keets suddenly losing coordination then dying.

[ByGraceAlone]

We just hatched out 9 Guinea keets from an incubator, with quite a history. The eggs were found on a farm and I have no idea how old they were when we put them in. The first one hatched while in the egg turner(!) and was happy and healthy, the next 5 hatched out a day or so later just fine, the last 3 I helped out and the very last one hatched about 3 days after the rest. This morning I found one dead with legs extended and neck thrown all the back. Today they all seem to be heading the same direction at various degrees. A few are laying down with necks thrown back kicking themselves in frantic backward circles. Others are up and running around but staggering and losing balance. I just found one dead buried under the waterer with maggots in the hay... So my first thought was botulism, but they seem spastic/stiff not floppy. I Sanitized their bin with vinegar and then iodine, washed water and dish, and put down clean paper towels instead of hay. Any ideas as to what this could be or how I can help them? Thank you!!