Bulling

[Ayers36]

If you have photos you would like to share of your coop/run and the feather loss that may be helpful.
What do you feed your girls?

Picking at one another can be from lack of space, boredom and sometimes nutritional deficiencies.
Have you observed the BA to see if she indicates that she is sick?

Adding more space may be one of the most helpful things you can do. If she is being kept from food - add another feed station.
I'm not a fan of separating hens unless you have to - I like to let them work things out, but if after you make some changes to your set-up and take time to observe behavior, then separation of the SLW may be in order - cage her away from the flock for at least a week, then re-introduce her. See if that makes a difference.

A reduction in egg production is likely caused by stress. Check everyone for lice/mites while you are at it. Is the SLW still laying eggs?

No one is sick back sides are clean free of flies mites
yes all six are still laying I did notice the slw sat on the eggs for almost an hour my son went out to get eggs came back said the slw was sitting on them then I went out 1.5hr later and she was still there so i encouraged her to move on wondering if that has something to do with it
I feed them layer feed and some kind of treat (corn scratch, frozen vegys, pineapple, oatmeal, or head of lettuce) every other day in medium portions to keep thier weight in order but they get fresh hand picked grass everyday after I let them free range for about an hour

 

[Wyorp Rock]

Try adding some space and another feeder to see if that helps.
The SLW sitting on eggs for a while... not that unusual, sometimes I think they decide to take a nap after laying an egg - who knows.
I would take time to really watch them and observe the flock dynamics there - a lot of times that will shed light on what's happening.