6 week old with balance issues

[K_UU]

About 4-5 days ago I noticed one of my 6 chicks (vaccinated) had a little wobble in her step. When standing she would seem to be off balance. I came on here to check it out, and thought perhaps vitamin deficiency, so I put some vitamins in the water and some antibiotics. She is unable to roost but has lots of energy, she's chasing bugs and her sisters, has a great (almost voracious) appetite.
She seemed mildly better the following morning but was sort of at a status quo after that, neither improving or getting worse. I gave everyone fresh water for a day vs vitamin laced water, and I noticed she seemed worse last night, more like she's slapping her feet down when she's running, more uncoordinated.
I also realized the vitamins I was giving her were not the full B spectrum. All farm supply stores were closed so I got her some human B complex and some Vitamin E as well per dosage I found on here. I also did a deworm of the group. I hope I'm not throwing too much at her at once.
She's only had her first dose of the B's and E this morning and I'm not sure what to expect.

IF you have been successful in treating a vitamin deficiency, do you have any advice? Actual "it worked for my chicken" advice? She's such a little sweetheart and I don't want to get my hopes up or get discouraged too quickly either and not give her long enough to get better.
Thank you!!!

 

[Eggcessive]

I would continue to give her the B complex and E daily. What are you feeding them? Hopefully, she is just having some temporary issue. If you would like to upload a video of her problem, it can be put on YouTube with a link posted here. Is one leg weaker?

 

[nuthatched]

What antibiotics did you give her? What did you worm them with?
It will take a few weeks for improvement for vitamin therapy.

 

[K_UU]

This is their:
Feed
They have access to the layer’s feed when everyone comes in at night to roost but haven’t shown much interest in it. They free range a bit around the run when we are home (the big girls free range all day)
The antibiotic was oxytetracycline hydrochloride soluble powder - wasn’t sure about this because she seems healthy otherwise, so I only gave 2 days and then second guessed myself and quit it.

Dewormer was piperazine dihydrochloride which I only started this morning and they are already crapping out worms. I had done my big hens about a month ago, not the babies obviously.
I’ll post a video in a bit.

 

[K_UU]

Update: no changes. She is neither better nor worse. She gets 1/4 tab of vitamin B complex morning and night, plus Poul-Vite in the water, and 400IU each morning. She eats it in half a cooked scrambled egg.
She eats well, isn't suffering. She does lay down more often than her siblings but I think it's because constantly balancing is exhausting.
She does scratch at her ears a bit - I've looked and don't see anything, not that I'm sure what I'm looking for. No discharge, but I'll look closer tonight.

 

[K_UU]

I hated reading through these when I was looking for help and never seeing the outcome, so I’m posting ours.
The slight stagger in her step started June 22 or so, she’s been given B complex and vitamin E daily since then in a small bit of egg, as well as in her water. She got slowly worse, nothing drastic over the past weeks but yesterday I was uneasy about her quality of life. Since she was showing no improvement at all, we culled her.
Moira was such a sweet little gal, it was a hard thing to do, but I knew it was going to be the ultimate outcome and didn’t want her to suffer.
RIP my little girl

 

[Eggcessive]

Very sorry for your loss. If you see any further cases like this, I would probably have your nearest poultry vet pathologist, such as at U of Guelph, to do a necropsy in case it was Mareks. Sometimes even vaccinated chicks will still get it.