Welcome to the forum. I understand what you mean by malaise as this describes how I feel at times, and probably many others.
Ross River fever can be very debilitating and takes a while to recover even after the virus has gone. You have used up so much energy that getting back on your feet is hard. Post viral malaise may be getting in on the act. I had a post viral fatigue many years ago and I had six months off work. Apart from feeling tired, do you have any muscle pain? I found this very uncomfortable and that it did not respond to many pain killers. I did find a slow release medication helpful.
It sounds as though you are fighting two illnesses, depression and the after effects of the fever. And yes, the fever could be the trigger for your depression. So what to do. I presume you have regular appointments with your GP and she/he knows all about what you have written here. If not then I suggest to rectify this ASAP.
I see no point in taking supplements unless you have discussed it with your GP. Advertising has a lot to answer for in this respect. Make sure you have a reasonable diet as this may well be more helpful than other supplements. Having said this I acknowledge that I take supplements but only because my doctors have recommended them.
Antidepressants are often a bone of contention. You say, I believe I can beat it naturally and I do not like all the side effects from them. No one likes side effects that are uncomfortable but how do you know there will be side effects for you if you have not tried them? I have a history of not tolerating ADs but I now take one that is fine for me. I once took an AD that caused me all sorts of horrible reactions but a colleague taking the same AD had nothing. There is no one size fits all with AD and unfortunately we may need to trial several before find one that works and is comfortable to take.
I have never met anyone who has recovered from serious depression on their own. Possibly it happens, I don't know, but getting professional help means it can be easier and faster than struggling on your own. Mostly we feel shame for asking for help or by admitting we have a mental illness. That should not inform our treatment. I suggest you go and have a long talk with your GP about the pros and cons of medication and the advantages of counselling of some kind.
Print out your post above and take it along with you. Write down all the feelings you are experiencing and talk about them. Come back soon.