I would guess that it is peck wounds, but fowl pox is a possibility. Are you seeing mosquitoes around, or do any of the others have scabs? Fowl pox is a virus that is spread by mosquitoes, and last 2-3 weeks.
How long have the sores been there?
I found with dry pox they looked like horrid scabs and then after falling off there was a red slightly bloody mark that formed a minor scab and vanished in a few days.
For older chicks and hens this took anywhere from a few days to 2 weeks. In these cases there were no other symptoms.