Hi,
I have always used a humidifier with my boys for a cold. It helps keep things moist so allow mucus to be coughed up/ aspirated from a nose much easier.
My son was in hospital for 3 weeks with bronciolitis, and their standard treatment is humidified oxygen. The studies speak for themselves.
As a side note, Eukybear is not recommended for young children as it can lead to lung collapse. I was advised by a senior pharmacist to only use baby balsam. Not worth the risk if you ask me.
Good luck and I hope your little one is feeling better soon!