Hi, my 74-year-old mother felt nauseous this morning and had to leave a movie. Tonight, she called out as she began to lose her balance while walking, and I caught her from behind. She told me she had begun to faint when she lost her balance and I caught her; had I not been there, she probably would have fallen on her face. She adamantly refuses my entreaties to see a doctor, even though she has health insurance. She claims she was just tired. What could the possible diagnosis be for the nausea this morning, and the fainting while walking tonight? What can I possibly tell her to convince her to get checked by a doctor?