My kitten fell about 20 feet and was initially breathing strangely?

I'm in a 2-story loft apartment and my kittens I recently adopted (about 12 weeks old) were playing upstairs and one must have gotten up on the loft wall and fell, as I just heard a loud thud behind me and saw the kitten lying there and slowly walking away. I don't think he landed on his feet, he might have hit the edge of the counter on the way down and he's pretty weak and uncoordinated still. He was initially breathing strangely, I could hear some kind of popping/crackling sounds and irregular breathing and he would just crawl under the table and lie down, not being sociable as usual. Now the breathing sounds and abnormal breathing seems to have stopped but he coughs once in a while. I'm not sure if the coughing is directly related to the fall as he was coughing occasionally the other day (both cats have been sneezing a bit since moving here, only been here about 5 days and I've heard it's normal for shelter cats to get a cold when initially moving).

I called the emergency vet and explained the situation and he told me he's not too worried, and to just watch him and I can take him in in the morning if I want to. Only thing I was really worried about was a pneumothorax, but don't know. Anyone with experience with cat falls and similar symptoms? Is he just a bit shaken up? If things haven't really improved by morning I'll take him in to the vet during normal hours but can't help but be worried.