Hi My Mother Has Been Taking Norfloxacin Whenever Lesser Antibiotics

Hi
My mother has been taking Norfloxacin whenever lesser antibiotics don't work. They always fix her up. However I can't seem to find a chemist who has this drug now. My mum needs the Sulphur-free tablet as she is allergic to Sulphur. Is there a worldwide shortage of this Sulphur-free drug or is it not produced any more?
I live in Brisbane Australia. I have tried a few choemists and each one says that it is nearly non-attainable now. Can u help?
Kind Regards
Garry Thomas