If it's got into the nail bed applying stuff to the nail will do sod all. A course of Lamisil tablets from your doc will sort it. Some docs reluctant to give them out, not sure why.
I know someone who is dealing with this: 'Trosyl' = tioconazole, painted on twice a day, on prescription. They've been told it'll be 6-12 months to be free, but tbh after about 4 months massive improvement, and the nails were pretty bad before.
got it on 1 big toe, been prescribed that curanail paint on stuff first but its doing sod all so I'll be going back asking for the tablets.I think the tablets can have some bad side effects