When I picked her up to take these pictures, she started dripping white foam out of her mouth. It is 90 something degrees outside, and she just got done chugging water, that might be why.
I see no sores on her body. She was born the week before Easter.
It looks like she's just growing in some new feathers. Chickens grow through several molts before getting their adult feathers, and if feathers are lost, they grow them back in.
She appears to be growing in new feathers. In the early months of their life, chickens are almost constantly replacing feathers on some part of their body. Then, at about a year of age, they go through a complete molt, when they lose basically all of their feathers and grow them back in.