Short answers, pulled from the story.
Most nosebleeds are caused by rupture of small blood vessels in the nasal mucosa, most commonly in Kiesselbach's plexus at the front of the nasal septum. Common triggers include nosepicking, dry air, blunt trauma, high blood pressure, blood-thinning medications, and nasal sprays used improperly.
Pinch the soft front part of the nose, not the bony bridge, and hold firm pressure for at least five minutes and up to thirty. Tilt the head forward, not back, to prevent blood from draining into the airway. Over-the-counter vasoconstrictors such as oxymetazoline can also help.
The medical term is epistaxis, from the ancient Greek epistazo meaning to bleed from the nose, itself built from epi (above, over) and stazo (to drip from the nostrils).
About 60% of people have a nosebleed at some point in their lives, though only about 10% are medically serious and roughly 6% of patients seek medical attention. Anyone whose nosebleed lasts longer than thirty minutes despite direct pressure and vasoconstrictive medication should seek medical care.
Anterior nosebleeds originate at Kiesselbach's plexus in the front of the nasal septum and are the more common type. Posterior nosebleeds arise deeper in the nasal cavity, usually from Woodruff's plexus or the sphenopalatine artery, and are less common but more serious and difficult to control.
In Filipino slang, to have a nosebleed means to have serious difficulty conversing in English with a fluent or native speaker. The phrase also refers to anxiety caused by stressful situations such as examinations or job interviews.