I noticed on one of my hens she had a spot pecked at on her back at the tail feathers, thought just been fighting for order, went out a couple days later to check and tend to them and noticed that now it was pecked down to the bone, so I removed this hen to inside in a giant wire dog crate, bought some wound cleaner at the feed store along with stuff they said works called pick no more lotion. I kept the hen inside for about a week, this wasn't working out as my inside routine and noise did make the hen jumpy so to say. I had to put her back out, in the time this hen called Reverse(she looked like a shunk when a chick) thats hurt was inside I notice two others my back and white one called Moo had her butt feathers missing as well as one of my reds had the same tail feather spot as Reverse, so I watch closely to see who is doing the picking, it came about my big yellow one called Dasiy. Since Reverse was making a mess of the cage and be loud and just all around anxious I decided to try to put her back out in the pen, when I opened it up I found Moo which I loved had been killed, to my surprise the same injury and spot on her tail end. I gave Dasiy a taste of the no pick, applied the no pick the others being pecked at. I let them out yesterday for a couple hours with Reverse outside as well, one of the red ones chased her and wanted to fight with her but Reverse bowed up and pecked back. Well this morning I get up go check on them and hear one clucking rasing a fit and go watch Dasiy and one of my reds has started to peck at Reverse again drawing blood, so Reverse is back inside again. I am at a loss, I don't know what to do other than keep Reverse inside till she is healed up but in this behavoir going to keep on or will it stop? I do have a small coop one from atwoods its the barn style coop had 6 now down to 5, could this be a room issue or something else, its been cold but also warm outside. I was told it could also be a vitamin problem, so I bumped the feed from 16% to 18% but need to fill the feed up with the 18% also got some life-lytes mega tabs to put in the water hopeing this will help. I do plan on adding a run to the side of the coop, but even this morning as soon as the door the pen opened Reverse came running at me with the other two chasing her like she was saying dadddy help me they won't leave me alone. I read also once chickens get a taste for blood they don't stop. I don't want to loose anymore my chickens but I also have a time stretched schedule with my work I tend to work long hours but have a injured chick to tend to. I am also afraid of letting them out in the yard they will fly over the fence but don't want to clip wings in case they need to fly up to escape danger, there is also two big dogs behind me that can stand and tower over the fence but have not showed signs of wanting to jump over at the chickens yet they just bark at them. Would they be ok to let out during the day to range and put up at night or let out for a couple hours while I am home to keep watch. I have to do something as its Daisy and one of my reds chasing and pecking at Reverse tail. Am afraid they will kill her like they did Moo. Sorry for the long post wanted to give as much detail and explanation as I could.