What is wrong with my manky toenail? Warning! Photos!

[Ferriting]

It's very grim, and very sore.

The left hand part is spongy and basically crumbles away.

It's definitely not fungal because it's been tested.

Who should I seek advice from and what may be the treatment? Thanks!

I would see a podiatrist.

I might get shouted down but Vicks vapour rub really does work. I'm dealing with the same problem now. Had really bad episode that couldn't be treated when I was pregnant 11 years ago but i persevered and my toenail grew back perfect. Silly me had nail polish on my toenails for six straight months and I'm back at square one .

See a foot healthcare practitioner

Tea tree oil works on my dad's toenails and they are like this. He was told this by a nurse!
I would go and get it seen to though