Rhode Island Red chick not doing well

Hello everyone. I am new to chicken health issues. I am hoping for some advice. I keep running into dead ends with a lack of veterinarians in my area that will see chickens. If I have to travel, I will. Until then, I am hoping for some seasoned wisdom.

I have a four week old Rhode Island Red. She has been wobbly for about a week now and can no longer support her body weight. All my other chickens are healthy. She is isolated from the flock. She is eating and drinking, and seems pretty content except she cannot walk. Her feet are splayed under her. Here is what I have tried/important information:

1. Isolating and keeping her under heat lamp
2. Vitamins, because I initially suspected vitamin deficiency
3. Probiotics
4. Electrolytes
5. Her eyes are clear, all orifices seem clear.
6. She is responsive to me.
7. She is pooping on a regular basis

She is not getting worse. She is also not getting better.

Here's what I did for mine: I used a tablespoon of cayenne powder to a pint of boiling water, steeped, covered, for at least 15 minutes, strained it and would give it cooled for drinking water. If I had enough time, I would let it steep until room temperature. When cooled I added about a 1/4 cup of honey to a quart.
I started fermenting her feed. I would give her 1 clove of minced garlic in her feed every day. When she stopped eating it voluntarily, I made a tincture from it and gave her that 3 times a day.
The cayenne is good for her and will cause her to drink more, which will help her get rid of toxins. You're doing the right things and looking for symptoms. Spend a lot of time with her since she doesn't have other chickens around. Mine almost stopped eating, I put her back with the others and she started eating again!

I also herbally wormed her.

Some chicks are born with congenital defects, and they will not survive no matter how well you care for them.  We usually lose a couple chicks around the 2 week mark. And again at the 4 week mark.  I don't count my chicks until after they have passed the 4 week mark and nature has done the work of culling out the genetically inferior or defective chicks.  

I know it's probably hard to hear but truth is, the chick sounds like a weakling and you certainly do not want such trait in your flock. Kindly cull her ASAP!

Sadly, what the two posts above have stated is the simple, straightforward truth about livestock: sometimes you just get bad stock and there's nothing you can do about it.  In nature, that chick would have been eaten by a predator a long time ago.  

If you purchased it from a reputable dealer, take her back and ask for a replacement bird.