I have some baby chicks, maybe 5 or 6 weeks old. They've been outside because temps in Louisiana are awefully warm. Guy at the feed store told me they'd be fine at this age without a heat lamp unless temps get in the 50's or so which they haven't. Got up this morning to put some more feed and water only to find two dead and one on the brink of death. I watched it turn his/her head back toward its back and eyes were closed, it got to a point where it couldn't stand anymore and just layed on it's side. Any insight as to what's wrong? I didn't give them any vaxes and am unsure if they had any. This is my first time raising chickens so I didn't even think to ask.