my BP has had un URI before and she "whistled" more of a wheezing sound. you could def hear her breathing, not normal. she was also producing alot of saliva- weird! so after a vet visit 115$ later and 2 weeks of antibiotic shots everyother day she was good to go!
but as everyone mentioned it could be shed blocking nostrils. the eyes going cloudy then clear is normal. when my bp is shedding i put a humidifer/mister on her to help out. she seems to like it- will lay directly under it.
hope that helps please be careful- these guys seem to be ok then crash fast