Actually, finisher is usually the term for feed given to meat birds as the last thing before slaughter. Yours is at an age for grower.
But I rather doubt that is her problem. I'd say the two most likely problems are heat and cocci, and of the two, I'd guess heat.
Whatever her problem is, I'd get probiotics and a vitamin/electrolyte supplement into her; both should be available at the feed store. You can substitute plain live culture yogurt, infant vitamin drops, and a bit of Gatorade or pedialyte if need be. Since she's been off feed I'd also get some egg yolk and applesauce into her. And put some organic ACV in the water. None of these will cure her but they will build her up so she can tolerate whatever her problem is.
You haven't mentioned how you are dealing with heat, at least on this post, and I don't think I read your other one. I've noticed several people on here mentioning simply dunking the chicken in water recently, which makes a lot of sense to me; I'll bet once a day in the heat of the day would do it, though you'd have to do some sloshing and ruffling of feathers to get the skin very wet.