Well, I'm still giving him the polyvisol 2x a day, I purchased Durvet Vitamins & electrolytes from tractor supply, this is a general livestock/poultry vitamin which when I compared to others (I believe nutri-drench?) seemed to be the most potent and complete vitamin they had, their selection was quite limited. This one is added to his water as is a b complex - human vitamin capsule 1 dissolved in a 2 quart jar of water. I am seeing no change at all which is why I'm thinking this is neurological and not a vitamin deficiency. On the plus side, he is definitely growing, but not as much as his siblings.
Do not give the Poly with the Durvet vitamins. This is overdose to do that. Just the poultry vitamins and the Super B Complex. Make sure it's the Super B, a regular B Complex is less potent and doesn't contain the C.
Okay, I have a few minutes so please bear with me and I'll explain a bit. Your chick is young enough that the extra B vitamins can make a difference in how his neuro system still developes. With humans, if a child is born with problems because the mother may not have been eating right, taking her vitamins, ill....there are so many things that can cause these things. Many can and will show improvment if the situation is changed even after birth. The addition of vitamins to human or animal can do this. Not always and maybe not 100%, but still a live functioning being, able to have quality and quantity of life. The Super B Complex has vitamin C added to it and I've tried the B and the Super B and found that it is the latter one that does the trick. Whether it is the addition of the C or not, I can't prove it either way, except through my own observations. Weird thing...birds synthesize, make, vitamin C. Not sure which word is more correct but you get the idea. I have only seen 1 poultry vitamin with added C and couldn't tell you now which one it is. Anyways, manufacturers figure it's not something that needs to be added right? The birds make it themselves! Hey! We get to save on an ingredient! Okay...but what if this little one can't make his or her own vitamin C? What if the problems passed from the mother were bad diet and this function, it should have, was one that didn't develope because of this? What then? Vitamin C is an extremely important part of the growth of nerves, skin, muscle....yadda, yadda, ad nauseum. Giving the Bs in a higher dose is great, but if you don't have the C working with them, you are fighting a losing battle. One or the other cannot do it's job alone.
Many of you have seen me go on and on about the vitamins....lol, sometimes it gets to me too,but it's important. There are certain ones, E, D, A, K....that are fat soluble. They stay with the body and are stored in the fat. Your bird isn't up and moving around, using up these fat stores, chances are you are givng them a harmful, if not lethal dosing. These can even cause pralysis if given in too high amounts. My links are not easily gone through to find what information I need, otherwise I'd add the ones pertaining to this stuff here. Sorry, it would probably take me hours to sort through them to find them. If you want to do a search yourself, look for vitamins and their functions, dosage and avian vitamin needs. next do a search on the feed you are giving your chicks. See if there have been any recalls or forums where others are having problems with some of the same issues you are. Never think that the feed is always safe. It isn't, just like anything else, stuff happens and ingredients can be left out or added in harmful dosing. Heads up at all times. You start seeing a problem with your birds, immediately think ingestion and check their feed first and then a check list of what else they could have gotten into.
I hope this helps you understand why I say not to give the Poly-vi-Sol and why I say Super B Complex.