I have young orpington and wheaten maran chicks, all from the same hatch, about 13 weeks old now. I started with 14 altogether, and I've lost five over the last month, three this past week. I've brought the last two in for a necropsy, but the results won't come soon enough to save the next one probably. Another one is sick this morning. The symptoms: they just become inactive, and stand in a hunched up position, chest kind of puffed out. When I examine them, I can't find anything unusual. Soft crops, crops not full, no sour smell from the beak. No sign of diarrhea. Clean bottoms. No sign of irritation from lice or mites, around the vent or anywhere else. Of the three that died this weekend, one stopped eating, but two continued to eat until the last day. They stood up until the last day when they finally went down. The one that's sick now wouldn't eat this morning and is just standing with a slightly hunched look. I see no sign of bloody diarrhea in the coop, and the sick chicks don't have evidence of diarrhea. They get clean water with apple cider vinegar, and they're on grower mash. I clean the coop regularly. They're on pine shavings, and are out in the run during the day. Any idea what might be happening? I'm getting desperate, as I want to save this Wheaten Maran pullet (one of only two) and don't want the rest to get sick. They all look healthy so far.