I am a beauty therapist, and the strangest thing started to happen on some of my client's toenails. White patches almost covering the middle of the nail plate appeared, especially on the big toes nails. It feels slightly coarse on the surface and it can almost been buffed away with a buffer. Not sure what it is. It doesn't start at the free edge like a fungal infection. I am not sure if I am doing anything wrong. I sterilize all the metal implements with G-Cide Plus and every client has her own set of nail files. I also use non-acetone remover and a moisturising base coat before applying nail color. What can it be, and how should I handle this stressfull situation?