Balding chick

[Iheartchickens7]

Hi Everyone,
I have a bantam cochin that is approximately 4 weeks old. I noticed about a week ago that it had a bald spot starting on the back of his/her neck. The skin is very dry and calloused and thickened. I have seen him/her scratching it but not obsessively. The bird is acting fine, eating drinking and playing. I have looked for bugs/mites and do not see any. The other three chicks do not have any signs of anything similar going on with them.
Just wondering if I should be concerned and if there is anything I can do to help out the little one. I hope these pictures are helpful. Thank you!

 

[86121]

Could the other chicks be picking at her? Perhaps put some sort of scentless moisturizer on it for now?

 

[Iheartchickens7]

I suppose they very well could be. I will look around and see if there is anything I can put on it for now. Poor thing seems to be losing all his fuzz faster than the feathers are coming in. Thanks for the reply!

 

[ParistoCapeCod]

I think the Storey book recommends pure petroleum jelly