I'm really sorry for your loss :grouphug:
Unfortunately my chinchilla died today. She was 6 months old and she had the same symptoms as yours. The only difference is that mine was eating well and drinking water till yesterday.
I am still trying to figure out why did it happen. I was only feeding her chinchilla approved pellets (that I have researched are appropriate for their sensitive digestive system), I changed her cage every couple of days, cleaned very well her water bottle, I have put sawdust on the bottom of her cage, bought her a wooden home, wooden toys to chew. She didn't show any sign that she had any kind of problem, she was eating normally, her poops were normal, she was running all over the room, climbing on my pillows, she was taking dust baths, chewing her wooden toys.
I am really sad, because I got very close to this small animal. Till yesterday she was doing well and today she had the symptoms that you described above (she climbed on my hand, stood still and didn't want to eat or drink anything, she didn't want to run as she always did when she was let out of her cage).
It was very painful to watch her trying to breath and not being able to help her.
Here in Greece it is very difficult to find a vet available on Sundays, so I had to wait until tomorrow Monday. Unfortunately this seemed to be too late for my little one. I hope she may rest in peace