Hi auorei, had same problem. I went to the chemist and got a product for nail strength and repair. Worked well. My nails also soft .Toenails got black but did not fall off. I just painted it on my nails.
I will never know whether I was lucky not extensive nail damage or product I bought worked. Either way oncologist said it was fine to use and it may help.
Thanks hun. I have nail strengthener applied before the black goes over it. But still tender. I will freak out if they fall off so far no sign of that, just tenderness. How long did it take before they get better hun? xx