Answer:
this...
is the vague pronoun in the sentence...
Sorry, but it's impossible to answer all your question because of character limit. But I suggest you to search via Internet sites that are specialized on story summaries. You can find what you need on such sources.
Answer:
Asthma
Reason why is because , if you look up the sympyoms to all of those bronchial airway only fits with asthma.