Our babies are on medicated chick feed and electrolytes once a day in their water. A couple have shown signs of lethargy, but usually not until shortly before death...... the one today didnt show any signs until we found her this evening and actually thought she was sleeping. They have room in the brooder to move to a cooler side if they feel too warm. All seem to be eating and maybe only slightly less water in indicate they may be in distress. I have noticed a couple who appeR to stretch out their necks and act as tho they want to chirp, but nothing comes out... similiar to their actions when drinking water.....
the baby we lost this evening had apparently just passed when I found her as she pooped in my hand as I scooped her out of the brooder, but the smell was HORRIBLE, not regular chicken poop smell at ALL. And seemed very watery
Sorry you're having to go through this and sorry the chicks are having a tough time. I'd call the nursery where you got them and see if there have been other reports of similar losses.
This is a real head-scratcher. Possibly their feed is bad? I'd change it given the situation "just in case". I'd definitely treat for cocci with Corid. I know you said they're on medicated feed but they can sometimes still get it. Young chicks are susceptible to it and that would be my first guess even though they're not exhibiting the "classic" symptoms of fluffing up although lethargy is one symptom.
Make sure they're on the large size pine shavings so they don't eat it. The fine stuff invites eating although I don't know if that would cause problems like what you're experiencing.
Pasty Butt can be fatal but you should be able to see that as there would be a hard plug of poo on their butt blocking their rears and making them unable to go. The horrible smelling poo may be a result of cocci and the only other thing I can think of is that a bacterial infection can do that. If it's cocci, you should see improvement soon after you start the medication. Sure hope you're able to find an answer. Best of luck to you and please let us know how it turns out.