It sounds like the chick is having stridor, just high pitched because she is tiny. Stridor is when something partially blocks the airway. It could be a small piece of feed, mucus or swelling of the tissues from a respiratory infection. When it comes from a piece of feed in the airway, it usually goes away in a few hours or overnight. It can be accompanied by sneezing or head shaking if it is a respiratory infection or disease. I would probably try to get some Tylosin powder online and treat the water 1 tsp per gallon of water for 5 days. This store and jedds.com usually have it in stock:
https://thecanaryfinchstore.com/product/tylosin-powder-for-birds/
https://thecanaryfinchstore.com/product/tylosin-powder-for-birds/