I was diagnosed with Inflammatory (HER2 positive) breast cancer 17 months ago and underwent chemotherapy including Docetaxol and Paclitaxol. I developed peripheral neuropathy in the balls of my feet and toes and I too had toenail problems - I lost both of my large toenails. My GP thought it was fungus and the registrars at the cancer unit didn't seem to know anything about it.
I finished with chemo nearly a year ago, but am receiving Herceptin and still have the neuropathy. My toenails grew back but they are starting to go black and die off again.
My GP has put my on a course of B12 injections and has suggested Carnitine and Glutamine.
As with most things, it seems you are your best doctor so surf the many sites on the internet for help.
Good Luck!