Would assume the greenish poo is from not eating. I personally would go ahead and start antibiotics if you can't figure out what is wrong for sure. You covered lice/mites with the sevin, wazine gets round worms, might try another wormer that covers more worms? With laying hens I always worry that it has something to do with the laying cycle and if she isn't she may have some problem associated with that. When you checked for a stuck egg, how was her abdomen, any changes since then? You might consider force feeding or tubing her if she won't eat.