T.C.
Eucalyptus essential oil is amazing for croup. You can use it a variety of ways: Put a few drops in a little bit of almond oil, rub it between your hands to warm it up, have his breathe deeply with your hands in front of his nose. Then, rub it on his chest. Eucalyptus oil molecules get into his lungs and is so healing. Also, if you have to take him into the bathroom at night with the hot water running, put some oil in a small bowl and let the warm air mingle with the oil to fill the bathroom with the oil. Very healing. If you had caught it soon enough, I would have recommended homeopathic spongia tosta. At this late stage, it probably wouldn't help too much. It is best in the very early stages of croup.
If you feel that your son is having difficulty breathing at any point, take him to the er. Things can go downhill fast if you are not careful. Most of my children have not had to go to the er with croup, although many of them had it. But, one of mine got it so bad. Had we not taken her in, it may not have ended as well. This was before I knew about the eucalyptus oil, but she still may have needed to go in. She was very little (infant), and was throwing up because she couldn't breathe. Yeah, it was bad.