Job Interview Help

I need some advice. I am absolutely horrible at doing interviews. I have gone to 4 interviews at a hospital that I want a job at where they use Behavioral type scenario questions during the interview. My background in nursing includes working for the school district as a school nurse, doing CM type work for an insurance company, and a few months in a psychiatric hospital, and several months when I worked as a PCTII at a local hospital while I was in nursing school. So basically, I have no hospital experience whatsoever. I do not in any way know how to answer these scenario type questions. I have a friend who graduated a year after me and worked at the psychiatric hospital for a while with me and had no other experience who got a job at the hospital (on a floor that I interviewed on and didn't get a job). I do not know what I am doing wrong but I am becoming very discouraged and really need some advice and help please.