Advice please - 16 chicks arrived April 18, all healthy, alert. They've been eating, pooping, drinking, sleeping fine. We've had cool days and nights, then temps warm back up. Have heat lamp at one end of brooder, food/water at other end and midway. Found one unresponsive this morning, later it was gone. Did some errands, came home to find another one gone. I raised heat lamp and removed bedding (non-slip drawer/shelf liner) which I'd read on this site and others that has been recommended to us. Now have piddle pads and nothing else in brooder. The chicks were at one end of brooder, making me think they were too hot, so raised red heat lamp and cracked windows a bit. The brooder is inside our coop, which is draft free. There are two windows in coop, opened each about 1", plus a 1" vent above door and another, larger vent at back of coop. Had to block door vent this morning because north wind was blowing in coop, sending temps in brooder 80 and below. They are eating medicated chick starter, and water contains electrolite mix purchased from Meyer Hatchery that's recommeded for use with new chicks. Put a little ACV in water today. They've all been spunky, alert, eating and running well...now the loss of two in one day has me concerned. They had Merek's vaccination prior to being shippped. Suggestions please!!!