Development of new pecking behavior problem?

Hello - I'm fairly new to this world. Raised 6 chickens from pullets this past summer (2014), lost 4 over the summer to predators (stopped free-ranging and built a coop inside a small farm building after that) and then in August, introduced 4 new girls to the group and a Roo late this fall. Interestingly, the remaining original 2 were the best of friends until a few weeks ago when the one (a Production Red) starting pecking at the feet of the other (a Barred Rock). At first I thought it was just boredom (they've been indoors since early November when we first got snow on the ground and terrible cold) but it got out of control. The red really seems to have just "gone nuts" - fighting with the Roo after the first few days (initially was fine), pecking at the BR to the point of drawing blood on her feet (started before the Roo came), pecking at the spray-foam insulation on the "entry-way" part of their coop when she gets out while I'm cleaning the coop and such (none of the others eat the insulation) - and then started pecking at another's feet (a Black Austrolorp). I gave up and have had her isolated in a dog kennel (right outside the actual coop in the "entry way" of our little building) for two weeks now, trying periodically to let her back in the coop and each time she goes straight for the others' feet within seconds of being re-introduced. (My vet friend was fairly sure the others had a foot infection that might have started this behavior so he recommended an antibiotic that they are ALL getting in the water - and the two pecked ones are starting to heal nicely now that the "problem Red" is removed). My concern is whether she'll ever be able to integrate back into the flock or if I just have to find a new home for her? She is a beautiful Red and really thought she was one of our best bets for a good 4H bird for my son - but obviously this won't work. Help? (Feed is all organic 16% protein by the way with what I am thinking is plenty of kitchen scraps and dried worm treats to prevent nutrient deficiencies but I'm open to suggestion) (And interestingly she continues to lay almost daily in the dog kennel but ALL of the others have stopped completely for almost a week which is odd....although some have some diarrhea so I'm wondering if it's the antibiotic). These girls are more worrisome than kids Thanks!