I'm having a problem losing chickens lately and quickly. It started off with a buff orphington hen acting lethargic and dying overnight. Then silkie cockerel not lifting his head up and backing up until he ran into something and laid down. Treated with nutridrench and selenium paste but would not eat or drink and died after a couple days. Next another silkie cockerel would sit and eat and drink little. Seemed like it couldn't make contact with food well when it tried. Wouldn't stand. Treated similarly. Died after 2 days. Tried to force feed and water both. Then an Ameraucana cockerel seemingly died overnight in coop. Now I have a silkie hen and a silkie cockerel having issues. One laying not eating or drinking and the other stands and tries to eat by has issues making contact with food. All chickens have been treated with ivermectin. Had a run in with coccidiosis a few months ago. Treating with corrid and wormer now, but not sure what to do! Any help?! I've also noticed some of my other seemingly healthy chickens are skinny. Thanks.