Failure to thrive in my new chicks. Please help.

[MixedFlock23]

A better photo. This is from a fecal smear from the Ayam Cemani (6 weeks old). What am I looking at? What do you think I’m dealing with? I can feel the keel bones on all my birds. Hens & chicks. This has been a tough month or so!
I’m going to buy Ivermectin pour on and treat the hens. (I saw mites/lice on some of them.)
I think I will deworm the chicks also. They have been outside to play for a bit (& the three six week olds are outside all day). Maybe with the cocci issue, the worms overloaded them too? I don’t know, but two of them are not responding to corid and are barely bigger than 2 week olds at 5 weeks old.

 

[MixedFlock23]

Chicken update: 7 of the 8 pullets are now laying! (Only waiting on my mottled Cochin) The bachelor cockerels seem to be enjoying their celibate lifestyle as well in their separate coop/run.
They’ve all recovered from whatever plagued their early weeks as chicks. No other issues have occurred and no other birds caught whatever my three (culled) hens had. I do believe it was a yeast overgrowth. My older hens just turned 5 years old this month and I do hope the hard parts are all behind us.
(Oh and that “worm” I thought I saw was an insect hair according to a microscope fb group I joined.)