X2. It sounds like they are overcrowded. If you bought one of those pre fabricated coops DO NOT believe the claims they can hold 6 or 8 hens. Often in reality they can hold 2 or 3,
Pictures and/or a description of your setup plus the number and breeds of pullets/hens would help.
Hi! Welcome! good idea to separate her. Can you post a little more detail so we can picture your setup? How old are your chickens? Any roos? What breeds(s)? How big is the coop/run? Were they already an established flock? Yes on keeping them cooped for a week if they're adults. You could let them out if you monitor, It'd be better if you fed them good stuff in/around the coop with a call first so they know. Best of luck to you!
I suspect the person who told you to confine them to the coop for a week may have meant to keep them in entire coop/run structure, not to shut them up in the upper roosting / laying quarters, assuming you have a raised box-type coop above an enclosed wire run?
7 hens would need 28 sq. ft just for roost / nesting quarters, and preferably more if confined for an entire week. So you'd need a coop with a minimum floor area approaching 5 x6 ft. And they'd get pretty bored shut up in that space. If confined in a small area for any length of time, they benefit from diversions like a head of cabbage, hay or weeds, ears of corn etc. so they don't start picking on each other.
As another poster mentioned, if these hens had not all been housed very closely together before as an established flock, it's a potential problem. You can't put strangers together in a small space and expect things to go well. Chickens have to be introduced gradually, and the more space the better. They can and do get brutal with each other, and once it starts it's hard to stop. You need to provide escape places like extra roosts, boxes they can go behind, etc.