They are finishing a bag of the Purina flock raiser crumbles. We just started to have laying hens so I’ll probably try and switch to a different food soon. They do free range all day. But I have two that were just a little younger then 16 weeks and we had lots left so I had been finishing it out. It has rooster booster added to it. I know no one can unless we test

it’s just so weird. I feel like we’ve had a lot of issues since getting them in March but it wasn’t until they went outside. But we’ve lost three already in the last two months just randomly. She’s refusing most food and water and I’m a little nervous with how little she wants to eat. I gave some egg yolk to try and get something in her and she did a little of that.
I almost swear by Starter Feed, Yogurt (ours LOVE "mixed berry" flavor), and Vitamins to get a bird to eat. Adding Fried Egg Yolk to the mix only sweetens the deal. If a chicken won't eat that, then they're definitely in need of help.
Hydrate her first; nothing else will work if she's not hydrated. Then, mix up some of our secret sauce or what Eggcessive has suggested, both from posts further back in this thread, then hand feed her if you think she's not eating. Being able to monitor a sick hen/rooster/chick via seclusion allows you to monitor both fluid and feed intake. Again, she MUST stay hydrated; get food in her next.
I don't know if this has been added yet, but this is a good primer on how to give a sick chicken fluids or liquid oral medications with a syringe or dropper. Pay special attention to the location of the airway. If you're ever feel like you're not in the right spot doing this, remove the device and reinsert in the bird's mouth. Be sure; you don't want to aspirate the bird.
https://bitchinchickens.com/2020/02/06/how-to-safely-give-oral-medications/
Getting a flock of birds is work; make no mistake about that. They almost always need a little something here, or something there, but it's a task I (we?) take on out of a passion for the unique nature of each bird, their individual personalities, and of course the side benefits of fresh eggs and so much frenzied fun in the yard. It just gives me a lot of joy.
You might have started off a little bumpier than most, but you'll get to a point where chicken keeping is a second-nature kind of thing. Sure, they'll throw you curve-balls from time to time, but you'll be able to deal with 95% of what afflicts your birds with a quick exam, a look at their stool, a crop check, a belly check, and more. It comes with experience. When you don't know what's at issue, come here or go the the vet...
Keep us posted! We're pulling for your girl!