3 week old chicks now in brooder temp is 85 degrees fresh water/ feed medicated starter... So weather last week was hot and I put the chicks in the outdoor coop at night for 3 days no problem then it rained....... and weather dropped to 78 degrees and I lost some of them.... I found some huddled and dead after a rain and I brought in other chicks.... they are all JUST FINE for 2 weeks and suddenly just stop eating, hang head and die with empty croop. Other chicks are running around fine. What am I doing wrong now???? HELP WHAT CAN I DO TO SAVE THE OTHERS?