HELP PLEASE! FAILED MY ENGLISH TEACHING JOB TEST

Can anyone head me in the right direction for medical teaching material. I've retired from a career as a California QME (qualified medical examiner) writing medical-legal reports for state-referred injured workers. While in Taiwan I was invited to teach a trial class at a medical english school (nursing buxiban) I tried to teach a bit of simple physiology but they chose not to hire me saying the students couldn't understand the subject material. Instead they referred me a couple of MD's to teach one on one. It seemed easy to complete a live College Tesol 3 course and teach plain English at a Chinese school but for medical english its a different story. For medical teaching, I can't find any of the amazing selection of materials available for plain english. I haven't seen any examples of how to present and make the subject interesting, especially when the students have a very limited knowledge of english even after 8 years of english in their school system. My Mandarin isn't good enough to explain medical words. I'd appreciate any hints on how to design a medical course and come up with workable lesson plans. Thanks in advance John