Actually, I started hand feeding her about a month ago bc I noticed that she was having trouble getting around. As far as I know, the others haven't been picking on her, but they do occasionally step on her by accident. From the looks of things, my barred rock chick accidentally stepped on her and made the sores in the process.
I make sure that she gets plenty of food and water every day. She seems to be healthy and can even go to the grate section of the chick box on her own to cool off. I'm just worried about her being in there when she's so much smaller than the others now.
I've never seen any sign of bullying, or injuries like this before. All 3 of them have lived together since they were tiny fuzz balls. I know that chickens are social creatures and need friends, that's why I hate the idea of separating her.