We received 7 (day old) chicks 3wks ago. We have them in a stock tank in the house with fresh pine shavings. I don't know the breeds for sure yet. They were a batch of brown egg layers. The chick I am to describe is black with some white. It may be a barred rock. They were all fine the first 24 hours or so. The 2nd or 3rd day one of the chicks began the head scratching on both sides of the head. It would frantically scratch then fall over on its back and look like it was shaking/seizuring for several seconds. It would get up and run under the heater. There were times it was still, but quite frequently it would resort to scratching. I called MPC where the chicks came from and they hadn't a clue. I saw these postings, but no clear solutions. Luckily the skin was not broken. There was nothing visibly wrong to address. One thought I had was that it got dust, food, or water in its nostrils and was trying to eject it. Or maybe a seizure. These chicks did not have the Marek's vaccine.
We just observed and pampered it making sure the other chicks didn't attack it when it was on its back. After the 5th day, the scratching just stopped. The chicks are 3 weeks old now and all seem fine.
I don't have a remedy to offer, just hope that it may be a temporary ailment or sensitivity that is not fatal. The MPC representative shared a personal story she had with a day old chick she had. It was fine when she picked it up but when she brought it home all it could do was walk backwards.?? This went on for hours maybe a day or so, then it just figured it out and walked normal again. Her point was that sometimes there are just quirky things that work themselves out.
Just trying to offer hope.