I don't know if you are a resident or have a Medicare card and/or health care card as I would suggest seeing a doctor. Even if you are just a visitor to Australia a GP consultation should only cost about $60 and I would ask them as there are 4 other medications for your problem listed on the PBS (pharmaceutical benefit scheme). The problem is you would not get PBS pricing (I think) without a medicare card.
The medication, Icaden (cream) is classed schedule 2 which means you should be able to get it from a pharmacy without a prescription if it is available. Go to a pharmacy and ask to speak to a female pharmacist (if that makes you more comfortable) and see what they recommend. Make sure you mention the allergy issue.
Good luck. :)
The Australian health care system can take some getting used to if you are new to it, but it is really pretty straight forward