Hi, I'm new to raising chickens. I've got about 20 adults that are all very healthy. As well, 15 adult guineas. I have about 15new chics and they are slowly all dying of the same thing.... their eyes swell shut, the birds become very lethargic, then die. These chicks are about 6weeks old now, kept in warm dry environ. I'm in oklahoma so it's been over 100 most days since I've gotten them. I use pine shavings for their bedding and change that out about every 2 to 3 days. Anyone have any idea what this could be? I've started putting a general antibiotic in their water(as of today). Any help would be appreciated.