Poult missing neck feathers

[Mckaykay]

I have 3 poutls all are 1 month old. I know I definitely have 1 tom out of the 3 . My tom and bird (A) are the same size while bird (B) is small and is missing neck feathers and has a white bump on neck ?

 

[Stipenvlerk]

Hi McKay Kay, Welcome to BYC!
If you feel like it's an emergency you could upload your question here:
https://www.backyardchickens.com/forums/emergencies-diseases-injuries-and-cures.10/