Our chickens are losing weight drastically. They seem to be feeling fine, but breastbone is sticking out and they feel so skinny. I wormed them 10 days ago with Valbazen and am about to start another round of wormer. About a month ago I integrated my younger chicks and went to an all purpose feed rather than layer feed. Some of them have had messy bottoms, but no blood in poop. I also went out last night and noticed feather loss on neck (doesn't look like picking, just like the feathers are gone) and mushy crops. I went out this morning and their crops were drained. Any suggestions appreciated.