HELP (new raiser) loss of feathers, green slimmy poo,drooling,cant stand

[cscscs]

I have am a new raiser and we have already loss 3 chickens and this one we found alive but she has a loss of feathers in a strip and i have to force her to drink but she eats by her self she starts to drool sometimes she pooped and it was like chunky seaweed looking and she keeps trying to "sleep"please help is it a disease in their pen? We have another thats been loosing her feathers but hasnt gotten this bad yet.