We had 3 hens that stopped laying, the weather was cold so we assumed it was to blame. 4-6 weeks after they stopped laying, 2 died within days of eachother. They had no symptoms until hours before they passed and then they were just lethargic. There was no bloody stools, odd discharges, or respiratory issue. One hen survived. A couple days after the mortalities, the remaining hen laid one very soft egg. That was about 4 weeks ago. Tonight we went out to find this. Any ideas?