Bumps on neck

[MaritimeFlock]

I noticed one of my girls had a yellow scab on her neck. I have been watching it for about four or five days now. It is looking better now. It looks like a normal scab now. But I noticed today she has bumps on her neck. Any ideas what this is?

 

[Wyorp Rock]

https://www.backyardchickens.com/threads/any-idea-what-this-may-be.1577394/