I don't have any recommendations but wanted to say, if you are going to travel that far I would probably ask if you could have a phone consult first and send them all the info you have already because the chances are that they would want to send you for a barrage of tests and it may be that they aren't available in Darwin and probably not on short notice in Sydney either. That way you could book them all in in advance then just have to make one trip. Wishing you the best of luck with it.