(I'm not sure if this should go under chicken behaviors, injuries, or managing your flock so if someone thinks it should be moved, please let me know.)
I went out to let my girls out of the run into the yard today to give them some roaming time and I noticed that the chickens were pecking at and picking on one particular chicken. They're all the same age and have been together two years. I picked her up to examine her and make sure they haven't injured her. I found she has a swollen toe (pics to follow) and blood on the top of her beak/nose area like they pecked at it and made it bleed. She is the same chicken that was lame for awhile last summer. I have already separated her in the partitioned part of the run I was saving for the chicks we have for when they get older.
I'm at a loss as to what to do. I don't know if/how she can ever be reintegrated or why they suddenly started picking on her. The 6 of them are in a 10x8 shed with a 10x12 run so they're not too crowded or anything.
I also don't have a coop for her currently but just rigged something up with sawhorses and a large plastic trash can on its side wedged in them with a plastic tarp over the top. I don't know if this is good enough considering we're supposed to get down to the 20's this weekend and it's not very high for her to roost in really. Any ideas on what I can throw together for her while she's separated would also be appreciated.