x2
If she doesn't appear to be unduly suffering, able to eat and drink, giving the vitamins, meds, and detoxification some time, could rally her.
Unfortunately chickens tend to be either well, or dead, or dead later. I've rescued a few to a long life, but those that succumb to something and nursed through often succumb to something else later which is why most breeders simply cull sick birds if anything other than a quick fix.
If you are really trying to be self-sustaining, with a regenerating flock, you may want to consider that philosophy. You only want the strongest and most resistant to further genetics in your flock. It sounds harsh, but it is best for the overall flock health.
It does sound like Marek's as she wants to eat and drink even though stumbling. Coccidiosis usually presents with a bird that is listless and does not want to eat or drink, sitting puffed and withdrawn, making medicating troublesome when they are this weak as you have to eye dropper them. (I've lost them later as it simply weakens their system too much and scars their intestines internally).
Vitamin deficiencies usually rally with noticeable improvement within a few days, sometimes almost magically, and then take a consistent regiment for a bit to fully eradicate, but as long as the bird is on a good healthy diet, the problem usually is gone.
I've not dealt personally with botulism or other toxins (known anyway), so can't make comment on them.
I wish the best for her and for you as you decide the best treatment plan.
LofMc