So sorry to hear about your little guy.

My sister's cat recently died from something that sounds fairly like what you describe. He developed a kind of gasping breathing, not because something was in his airways, but because his chest cavity had filled with fluid and his lungs could not fill with air. He was treated initially for hairballs, and then allergy. By the time they figured out it was congestive heart failure, it was too late to put him on any kind of treatment.

I am not trying to freak you out, and I apologize for sounding this distressing note, but if this is what your cat suffers from, and you catch it soon enough, perhaps it can be treated.

Best wishes to you.