Let's start with what you have on hand. Do you have any of these products?:Do you just mix one whole crushed tablet in their food?
Nutri-Drench for Poultry
Poly-Vi-Sol (human baby vitamins)
Vitamin B-Complex (tablets)
Vitamin-E (gel, paste, or liquid)
Selenium (200mcg tablets)
Tell me what you have available to you, and we'll go from there.
I had to re-read the original post to refresh what's going on. Note that I mentioned that the one that has her head tucked down could be the beginning stages of Wry Neck. I'd start with something like 2-3 drops of Poly-Vi-Sol and a 1/4 tablet of Vitamin B-Complex mixed in about 1/2 TBSP of Starter Feed with about 1/4 TBSP of Yogurt. If you have Vit-E and Selenium onhand, you can a 400IU of Vit-E (one geltab) and 1/8 (25mcg) of the Selenium tablet into this mix as well. Make enough to make about 4-6 pea-sized balls of this moist mix. You want it moist and flavorful so the chicks will eat it on their own. The yogurt, while also promoting good bacteria in their digestive tract, has a taste they seem to like (ours like "mixed berry" flavor).
Here's a good article on vitamins needed by chickens for healthy development and what can go wrong when they're deficient in them:
https://www.thepoultrysite.com/articles/vitamins-and-minerals-important-to-poultry