Came home today to find one of my 13 week old pullets dead. I kept them ( there were two) in our garage, Although she was eating and drinking last night, I now realize she had been acting a little antisocial yesterday. I feel horrible for missing the signs. Now I need to know what to do with my lone pullet still in the garage. She appears to be unhappy, but healthy. I could not find any lice or mites on either bird, but I suspect that must have been the problem. I am treating for that. I have three chickens out in a coop which I am also treating ( seven, clean sprayed coop). So my question is when can I safely add my 13 wk old to the flock? I had planned to wait until 18 Weeks when they could start on Layena, but I cannot see keeping my one chicken alone that long. She seems miserable by herself. My pullet is an Americana who has been fed chick start and grow. My hens are a Cochin, a Wyandotte, and a red sex-link.