Bullying or normal pecking order behavior...I'm worried.

I just adopted two new chickens the day before yesterday from a lady who is going out of the egg selling business after losing two of my hens on Sunday after our new neighbor's dogs tore into our pen and got them. We had three chickens and I got first eggs from two of them on that day before the dogs got them. We had one chicken, a Golden Sex-link (4 1/2 months old) left and luckily she was one of the layers and has given me an egg every day since Sunday except for Tuesday. Now she is obviously at the top of the pecking order since I added in two new chickens who are only slightly younger than her (4 months old). Neither of them are laying yet. They seemed to all get along great the first day together. But now, my new Barred Rock is especially being picked on, literally. I have seen my Golden Sex-link chase her and keep her from going inside the coop and keep her away from the feed bowl. The Barred Rock runs hysterically anytime she gets close to her and tries to hide in corner of the pen. I have even seen the Golden Sex-link pull feathers from the Barred Rock and peck at the feather that comes off. Several times I have walked out and seen the Barred Rock in a corner of the pen like in the picture not moving...I think the bully is being so aggressive that even if she goes inside of somewhere to hide, she just gets cornered as the bully chases her and pecks at her. When I try to pick her up to look at her the bully even tries to peck at her as I'm picking her up (jealousy) I thought she'd be happy to have new friends after losing her old ones. Yesterday I stuck the naughty girl in a kennel for a few hours before dark (took her out at night time because I figured she'd just be sleeping anyway) but when I checked on them this morning, I noticed the behavior was still occuring, so I put her back in the kennel. Not sure where to go from here...Questions:

Since chicken had feathers pulled, should I treat her with anything medicated?

How long should I leave bully in the kennel? (its a small kennel maybe 1'x3' but its all I have)

Will being stuck in kennel stress her out and cause her to stop laying for a while? (just curious, still more concerned over safety of the other girls)

Any other input or suggestions? Please!!

Thanks

You shouldn't need to treat where the feathers were pulled if there is no blood. If they have large bare areas, you might want to put saddles on them to discourage the behavior and prevent sunburn (see link.)

Since your "bully" was alone and others were added, I'm not sure the kennel will work. Usually it's done for a week, out of sight and hearing of the rest. Probably what would work best is turning them all tino a much larger area and setting up another food/water station, if that is at all possible.

https://www.backyardchickens.com/a/patterns-chicken-saddles

There has been numerous discussions on integration. Chickens by nature, is territorial. Merging new birds are always stressful for chickens and humans alike.

If you do not have the facility for next-door-neighbor strategy, then use stranger-in-the-night. After they all go to sleep, put the new birds on the roost with the current occupant. In the morning, they will look at each other and puzzled, thinking "I" dont remember who is the top bird and proceed to resolve that issue by a little fight. The winner usually would showboat and does not chase after for a kill. You also should have secondary feeding and watering so the loser can take refuge.

Chickens are social/flock animals, when I had a lone bird, she was quick to accept new birds.

Thanks Judy! I've never even heard of a chicken saddle - maybe I can make my own... Even though I've seen feathers pulled from her back and tail, as you can see in the picture, she does not have a bald spot on her back but I notice when I picked her up, a lot of feathers missing from her chest - I don't know what is causing this, she wasn't like this when I brought her home so either she is doing it or the bully is doing it. Unfortunately we can't create a bigger space at this time without letting them free-range and I know the neighbors' dogs will have a feast if I do that. We are hoping to get another pen soon that is larger that is sitting on a family member's property and who doesn't want it. What we have now that you see in the picture is small - 42 square feet in the run and 24 square feet in the coop but I was hoping it would be big enough for just three chickens and actually before my other two died, they got along great in it...I just wish my other chickens hadn't died, I really miss them and had gotten attached

Good idea ECBW! I should have just put them in at night, I would have never thought of that as I just put them in there immediately when I got them in the afternoon. I'm just puzzled because I watched them for a while after first introducing them to each other and it seemed to go well, they all walked around and pecked at things and clucking just like normal, there was nothing aggressive from anyone. It wasn't until the next day, (yesterday), that I noticed some inappropriate behavior. It seemed like normal behavior at first and I was unconcerned because my hen ran the other two out of the coop and made them eat after she finished eating but only let them eat for a few seconds before violently chasing them off. I think she is trying to be queen of the roost and is doing it wrong, lol. Where my new ones were living before, they were not pets and I remember walking into where the chickens were and all of them scattering and panicking because humans walked in. I wonder if this scaredy cat behavior by the other chickens is somehow causing them to get picked on...well really only the Barred Rock.

On the saddles, I've made a number of them, out of polarfleece, but sweatshirt material would work well. I usually end up tossing the first try, but the next one fits well enough, haha. I also don't bother with the tail hole, just the wing holes.