Bullied hen ?

Hi mollymuggles, it does sound as if she is moulting from what you have said.  The new feathers emerge from spikey quills.  The are not keen at being picked up when the new feathers are forming as it can be painful for them so that might be why she is keeping her distance.  Try to entice her closer with a treat so that you can get a closer look and just check she has no injuries as the other hens might peck at the newly forming feathers.