Why might a medical professional prescribe narcotics to a patient?

Why is it that people at first would be nice then they shut you down? (school matter)

Which action is characterized of mental illness 1.brushing teeth every hour because ones mouth feels dirty ? 2. forgetting to eat breakfast on a busy day? 3.crying three days over a relationship breakup? 4.feeling embarrassed about going to school after failing in front of friends?

Ihave a really high metabolism and only weigh 70 pounds (13 almost 14). people always ask me two questions: do you ever eat and how do you eat so much and stay so skinny. i am worried that a high metabolism wont me forever. what are some safe steps i can take to maintain being fit. (also, i already work out i am a dancer so i get cardio a lot)