Don't be alarmed:
Reverse Sneezing (Pharyngeal Gag Reflex) - VeterinaryPartner.com - a VIN company!
I thought I'd post a vid of Momo reverse sneezing. I know some folks are bewildered & wondering why their baby is makin such strange sounds...I sure did.
When this happens, I cover his nose or rub his throat gently so he'll swallow & he'll stop. He also stops on his own, but if I'm there, I want to help him.
It can be caused by hair, lint, dust tickling the throat too. He also does this when eating & drinking sometimes.
A collapsed trachea is different whereas rubbing the throat will cause the attack/honking sound.