Hello, I am posting again about Della because I am wondering if she may have sustained a head injury. I have been searching my mind and there was a time at about 2 weeks old that I was transporting her with a screen over the box and it fell on her. It didn't seem that heavy but she chirped loudly and shook her head. I feel so horrible that I may have caused this. Eating and drinking and pooping all normal but she just sort of lumbers along and cannot make it up on any of the perches even the lowest one which is just a small box. She stands looking at these things like she WANTS to get up there but has no clue how. I've been noticing her lagging behind for about 10 days now. The other 4 birds are all doing fine. They are on medicated chick feed with occasional chick scratch. They are in a large brooder (sideways fridge box) with pine shavings and 3 levels of perches. There is no visible sign of trauma but she has some redness at base of feathers as I think she is over preening?? I haven't seen anyone one pecking or bullying her and she is same size/weight as others. Maybe preening is easy activity while laying down which she does a lot. She also shakes her head more than the others. Other than her lack of coordination and propensity to lay under the lamp a bit more than the others she is energetic and friendly when awake. I'm writing primarily to inquire if there is any chance this is a disease that could spread to other chicks (all 4.5 weeks old). Thank you in advance for any advice!