Hi Sambo, did some research on the medal. First of all the international committe of nurses (usa) in 1954 decided to honour florence's nursing from her past, but did not get recognised by government authorities till 1972 worldwide, so the medal could be from any country issued, possibly Australian nurses organisation between 1954-1972. I am not sure if the red cross issued this as they have there own florence medal which they have been issuing too which looks like a cross with florences image on it. My best bet it is 1960-1970's, find out about the area you found it?, it may hold a clue? hope that helps, nice find.
Cheers George HH