Turner went to bed fine tonight, but around 11pm he woke up coughing. It sounded strange, so we went to check on him only to find that he was running a fever and having shallow breaths. His coughs sounded hoarse and strained.
We turned on the hot water in the bathroom and I sat in there steaming with him while Traci looked up some stuff on the internet. We put his humidifier in his room and rocked him until he calmed down and got his breathing back to as normal as possible.
This is our first bout with the croup, and it's no fun to deal with. Turner is doing fine now, though (writing this on March 2).