Are you brooding them outside in the heat? I believe Texas is almost as hot as the place i live. (100-110). If this is the case, its waaaay to hot to brood them outside. For my 11 girls who are almost hens now i have a .UV blocking shade cloth, a fan and mister in their covered run and a fan in the window of the hen house. All this is necessary or my girls wouldnt make it. Even though their run and house is under a big shade tree.the little ones just cant make it in that kind of heat as they do need a warm side, its equally as important to have a cool side they can regulate body temperature with.if you feel heats not the issue,, then could it be coccidosis? Symptoms are lethergy, extreme sleepiness, puffed up appearance, foamy poo, loss of appetite and they may or MAY NOT have blood in their feces, depending on the strain of cocci and how far its progressed. If this is suspected treat as soon as possible with Amprollium. The brand name is Corid or Amprol depending where you live. All chicks get treated and it wont hurt those who dont have it yet. I really do hope this helps a bit and do sincerely hope you can find out the cause of their illnesses. Im so very sorry you lost so many. Thats so hard.. i wish you the very best.Good luck.