Thank you very much for telling of your experience Busy. It is frustrating that it still came back for you, and interesting that the next doctor did not want you to have another dose.
Have you tried getting shoes which don't pinch? I think my toes got crushed by a dropped instep causing my foot to roll inwards. This created pressure on the toes which damaged the nail and let the infection in. I am not going to risk any tight shoes and am going to get a good orthotic to put in them.
Maybe try changing to natural fibre tights or socks, and always wearing clean, disinfected ones? One poster mentioned the importance of scrupulous cleaning of all implements and clothes, and someone mentioned tights being culprits.
(I read that non cotton gussets in tights are bad for thrush and candida too, so the tight nylon around the toes must make the fungus more likely to grow.)
I've got Eucalyptus oil too, as I read some people had found improvement with Vicks Vapour Rub.
I am also going to order a UV c light intended for curing nail varnish, as some have suggested.
Another step is to try daily soaking (30mins) in vinegar when I can find the right foot-sized container (I think a normal washing up bucket would use too much vinegar over 6 months/1 year as I read "Add a cup of vinegar" to the water".)
I never expected so many replies. This thread is very helpful for me, not only for practical reasons, but because it is comforting to know how horrible other people find this condition to be.