We have buff orps, NH reds and a bunch of guineas -- 5 weeks, two days old today. In the last two days, we've lost two of them. One red and one buff.. it looks like they just lay down and died. No malformations, no injuries and no trail behind them of excrement from the process. Two days ago everybody was playing .. flying around in the brooder and .. well being chickens. This morning, most of the buffs and the reds both are lethargic - although eating, drinking and pooping as usual. They are not panting.. they're just "roosting around" not doing much of anything.. a little pecking at the feed, water and yard veggies.. but mostly just staying still. The guinea's are fine. I'm VERY concerned that they are sick and don't know what to do. The only change we have made in the last week is the feed from the HMC to Purina (they were out of everything but the Purina) They do eat "yard veggies" daily.. no changes there either. I'm watching them closely and changing water more frequently, and I took the new feed out, just in case.. other than that, I don't know what to do.