If it sounds like a squeek it could be laryngomalacia. It comes in varying degrees from intermittent while sleeping to all day every breath.
My son had it severe, and my 5 month old has it mild.
Try to get it on video (audio) to show to your doc. They can refer you to a pulmo to be sure it is a malacia (there are several like laryngo and tracheo)
It is from an underdeveloped epliglottis. Usually harmless and outgrown by 2. But can be a sign of reflux and other issues.
I think there are some sound samples on you tube.
Katie, mom to Olivia (97), Veda (98), Franky (2004), Wendy (2005), JoHannah (2007), Thea (2009) and Sunny (2011)