My baby chickens keep dying one by one

[Smalltown1987]

Hello all,
This is my first time posting in this forum, while I am not new to raising chickens, my family has had them almost continuously for the past 15 or so years. I am having a problem, we just recently got some new baby chicks and they all died one by one. We then went and got some more from the same place. We thought this batch would be better, as it has been slightly over a week since we got them and they were fine, now they are just dying out one by one like the first batch. I do not know what is happening, in the 15 or so years of us doing this we have never had this much of a problem. (as a note we have raised chicks before) We do not know what the problem is they do not have poopy but, the one that did I put in a slightly warm water bath and got rid of it, now she is fine. I also moved the lamps so that there would be a shaded area. Any help would be great, we have already lost two and are about to lose one today, I expect she will be dead by the end of the day. While it is most likely too late to help this one I really don't want to lose anymore. Any help would be great. I could post photos of the chicks and cage but it will show the dying chick so I don't know if that is appropriate or not.
Please help

 

[Smalltown1987]

An updated note, I went ahead and pulled the weaker one out of the cage and put it under its own heat lamp and have been giving him some sugar water and she has perked up, she is now standing and is making sounds, which sound the same as the other three. So I am wondering if the sugar water did something or if she is still not out of the woods yet.

 

[Smalltown1987]

Another update, so I thought she was getting better, but then she just fell over, she is back up now. Although I have never seen anything like that before.