What kind of feed are you giving them?
I give all my chicks a mix that I make which includes einkorn, coconut, millet, quinoa, sesame seeds, brown rice, coarse ground pumpkin seeds, coarse ground sunflower seeds, nyjer, flax, DE and powdered kelp.
I also sprout organic wheat and occasionally organic rye for them.
All the growing babies get some raw ground beef or liver mixed with liquid D and a little extra powdered kelp, sometimes topped with raw minced garlic or a drop of oregano oil thoroughly mixed, a several times a week.
Their water contains Save-a-chick vitamin/electrolyte supplement (contains vitamin D) and sometimes the probiotics by the same brand. I put ACV in there when I have it on hand.
Oh, and I sometimes give them scrap minced veggies and some fruit (blueberries today)
Their symptoms are weak legs. Not paralyzed and they are still alert, just weak.
I have dealt with severe vitamin d deficiency before in chickens when my vitamin supplement (in the water) oxidized from improper storage. This was before I supplemented additional D. They all had symptoms like this which is why I ask.
I am fully confident they will recover after a day or two of double dose vitamin d and extra outside time (it has been raining almost every day tho) but was just curious if anyone knew if their requirements are naturally higher (so I can prevent it happening again).