These guys are right, you cannot treat, cure or diagnose.
It isn't easy to really diagnose fungal infections. It generally requires taking a clipping and sending it to a lab so most Doctors will err on the side of caution and say "most likely" and recommend an over the counter creme to keep under control while the plate grows out. If it doesn't then Doctors can take additional steps.
As an indicator, a large majority of people have a fungal infection on their toes though it is usually superficial. Deeper infections will generally swell the plate and have a distinctive order. You really do want to avoid working on plates like that as you will be releasing an excessive number of fungal spores into your breathing area (these spores are everywhere anyway, but you want to avoid excessive exposure if you can help it).
An over the counter creme may help the client so she may want to try that out.
If it isn't a fungal infection, its a pretty serious case of onycholysis (separation of the plate from the bed) which can lead to an infection. It could also be psoriasis of the plate (which contributes to onycholysis).
HTHs!
