This is odd, but my 6 month old puppy Pomeranian Kola is making a phlegmy gurgling sound when he is breathing. This only happens when he is moving. When he sleeps you can't hear it. We were at the park yesterday and he was heaving to get something out like a hairball or something. He was on leash and didn't ingest any foreign object that I could see. Since then he has had this sound when breathing. He doesn't seem to have any distress. Any suggestions to make this better?