only one symptom, can't figure it out

[walkingcrow3]

I have one two month old chick that has raspy/gurgling breathing, I removed her from the others right away and isolated her. She has no paleness, eyes, mouth and nostrils look very healthy, feathers are healthy, feet are healthy with no warmth to them. She is eating and drinking just fine too. Stools look normal, no green to it no runny poops either. The crop feels good. I used vetrx for the apparent congestion, other than that I don't have a clue as nothing matches her illness. all the ones I have read have other added symptoms and this chick doesn't have anything but the gurgles and congestion.