I bought 2 - 2 day old RIR female chicks. They were both healthy but when I brought them home. After about 3 days, one seemed to yawn excessively. After a few more days, I realized that she was struggling to breathe. Meanwhile, she was straining hard to poop. While she was straining, she would loudly squawk. Her vent became red and swollen and protuded. I often had to gently squeeze her vent to get the remaining poop out. It became harder and harder for her to breathe and she eventually became too weak to make it to the food and water bowl. I gave her water with a dropper and she seemed able to swallow it with no problem. I found her dead in her cage yesterday. The remaining chick cries constantly and wants to be carried around. My question is two fold. (1) can anyone venture a guess as to what happened to my little chick? (2) Should I buy another chick as a companion for the remaining chick. I called the store where I bought the chicks and they do not have any left from the same batch so they would be close in age. Is a few-day-old chick too young for the 16 day old?