Pain On the Forehead When Descending Fron High Altitude

Im a medical student studying in Moscow Medical Academy... A close relative of mine recently went for vacation to Switzerland.She is 33 years old and is single. Well, to cut the long story short, she complained to me tat she experienced the worst headache of her life when she ws descending down the alps...she described the pain as pricking pain on her forehead that lasted for abt 15 minutes, and ones she had reached the base the pain wore off.... i do not know if it is significant, but she had nose bleeds a few days befor that, but she assumed that it ws due to the heat. She ws diagnosed wif breast cancer of the early stage 2 years ago, but ws then treated with chemotherapy n radiation, n she is fine ever since. Her doctor recently told her that her blood cholesterol level ws pretty high. Pls do shed some light upon this predicament. Even if it may not be medically significant, i would appreciate it if some one could let me know the cause of this headache.