HELP blister on chick

[Rashid100]

Hello guys. This morning i noticed an odd blister on one of my button quail chicks. He also looks very dull and isn't running around like the others. What exactly is this and what can I do about it? Any replies would help a ton!
Thanks

 

[lcertuche]

Maybe an insect bite? I can't tell but if they are pus filled I would think infection. I really don't know anything about quails however. I wish I could be more help.

Sorry this is edited: If I was you I would try isolating the bird until I knew more.