Hmm, they get an organic feed that I buy from a local farmer. He said that it wasn't a protein problem or he would have problems. He said sometimes you just get a bad hen with a chicken and that some are just more aggressive. He said the kind that we had (white leghorn) wasn't great for small outdoor flocks. They have a lot of room, a large coop and a 900 square foot garden they get to roam all day that is full of bugs and even little field mice occationally (super funny when they would fight over who would get to eat the mouse.) Her feathers are growing back, but I will try to add some of your other suggestions for protein. Thanks! And what about the cold? Any suggestions? We brought her inside last night because I get nervous that she will get too cold outside. She seems happy and is still laying 4-5 times a week.
the amount of protein birds need is easily influenced by living arrangements. it'll be different for birds who free range than for birds who have killed everything in their run. snacks (scratch, kitchen scraps, etc) for the birds will throw off the amount of protein they actually eat. so, even when the feed is adequate number wise, it may not be adequate in reality.
with the cold, the garage is probably fine if it's draft free. If you're really worried, you could provide a heat lamp over the corner of her cage where she can go warm up if she needs to. that way you can tell if she feels cold or not.