@ Robert sorry for the lose you are going through. Chicks management is very critical and very stressful especially if you start it wrong. Remember to go through chick rearing successfully it calls for close attention as one can get contented by having all that you fill is right done yet only one lapse collapse the entire effort. Example you can have your chicks vaccinated on timely basis and fail to observe other biosecurity protocols, this way other disease more so bacterial will get introduced into your flock and affect them. If you haven't gone through elengo course on poultry management especially chick brooding kindly consider doing so. For now share the signs including photos of the unit for further help in problem diagnosis. Be generous with the photos as possible.