Ronald McDonald house would be the first place I would call. They have accommodation for families close to the hospital

We have been in the same situation. We have to go from Adelaide to Sydney to see a neurosurgeon. Your first point of call is to contact Ronald McDonald House in Melbourne. They have accomodation that is not too expensive specifically for families who are coming from the rural areas or interstate for medical appointments. Often they are given passes to zoos etc that families can use for FREE. They have a great support network. I wish I could speak to you in person to reassure you and tell you more about Ronald McDonald House (check out their website). You may also be able to get financial assistance for airfares from Variety, Redkite but Ronald McDonald can help there.