Hallo Kia
I'm in the UK, found your posting about arachnoiditis by accident. I'd like to think that my experience may give you a new view.
I have had arachnoiditis for more than 20 years, knew about arachnoiditis long before I learned about the trauma (spinal fractures and brain damage) that in my case caused arachnoiditis. Whilst investigating the cause of my arachnoiditis, a radiologist gave me the following information(1) and a doctor involved in a cluster of cases where myodil spinal injections prior to X-ray gave me informations (2) and (3).
1 - Check your MRI scans. These come with a variety of white lines, maybe labelled a-b, c-d, 1-2, 3-4. You get the idea? I haven't looked at your scans because I'm not a medical professional. If you look at the white lines, look for another matching scan - ie an MRI cross section of the spine showing various white lines such as a - b, c - d, e - f etc will have a different view of each of the same areas, so by counting the white lines and the notes on the lines, you can find out if you have all your MRI scans or if there are some missing. (When my spine was MRI'd there was a pile of scans at least 4 inches thick).
2 - Arachnoiditis (an inflammation of nerve roots where they exit the spine) will show on the MRI as "little white dots" at the spinal cord. (Understand this is the most basic of descriptions as I am not a medical person) so know what you are looking for. The "little white dots" are essentially the scar tissue caused by the inflammation. I think you mentioned disc compression? Were the nerve roots compressed where they exited the spinal cord? Do an internet search for the nerves you mentioned. The right search will identify what part of the spine the nerve come from. Did you have X-rays of those particular areas? Did you have spine X-ray with a myodil dye injection? Myodil is not now used because it was a known causal factor re arachnoiditis.
3 - Understand that arachnoiditis is an iatrogenic disease, which means it was caused either by doctors or their treatment. I was reliably informed that the reason it is so difficult to get a diagnosis is because it is proof of clinical negligence. I'm surprised you are having such difficulty in New Zealand as I thought in your country they had a "no fault" med neg culture, unlike here in UK.
It sounds as though you have been very sick. What put me back on track and made my condition liveable is that I was sent for exercise in a hydrotherapy pool. At first the exercise programme was a nightmare because my bones and nerves were so badly damaged but it took about nine months for my body to start to work a bit better. I have heard a lot of people with arachnoiditis say "oh, I can't do that" and the words everyone with arachnoiditis uses is that the more they do, the worse they get. Well, you can push past this, it takes real determination and a lot of hard work but if you persevere, you can get there. What I'm saying is that if your legs stop working, walk a little bit further (it will hurt but just do a bit more than you think you can do). If your head hurts, instead of taking pills and resting, read a few more pages of a book (you might have to read them again another time but do it anyway). You need to stop thinking of what you can't do and try to do a little bit more and eventually it will be less of a problem. My health is by no means good and I haven't been able to work for over 20 years since my accidents but I do have a quality of life that I would never have expected possible when I first found out about arachnoiditis.
Best wishes
Roz