Hi, I am still very new to raising chickens. We bought our first chickens in March 2015. Everything has gone well so far. We have two silkies, 2 Easter eggers and one amberlink. Recently, one of my silkies has become very broody. She lays on all of the eggs but she has gotten to the point that she doesn't leave the nesting box except briefly to eat and drink (even when there are no eggs).. We had our first frost last night and she has not come out at all this morning. When I tried to gently check on her, she appeared to be shivering. None of my other birds are acting strangely. They are going about their usual business. Is she possibly having trouble adjusting to the cooler weather? Or could she be sick? Thanks in advance!