The past few days my son has sounded very congested at night and when I put my hand on his chest I can feel his belly expanding a lot with each breath. The belly breathing doesn't seem to be constant all night, but quite a bit. He seems like he's struggling. ☹ During the day he's totally fine - no congestion or runny nose and his energy levels are fine. And he doesn't struggle during naps, just at night. We live in Colorado, so we're at elevation and the air here is dry. How worried do I need to be? I haven't seen his chest because he's clothed.

Fyi, we have a humidifier about a foot away from his bassinet and a fan going in the room. I'm going to buy a new air filter for our heater today.