It sounds like that skin infections such as the "athlete's foot" or the "jockey's itch", or "grey finger-nails", "grey toe-nails" are commonplace, and are not a big deal.

 "Grey finger-nails" and cracked hand or palm skin do bother a lot of people since they are particularly tough for treatment, and greatly affect the cosmetic beauty of people.

 All those symptoms are caused by the so-called dermatophytous molds, mostly 3 genera: Microsporium sp., Trichophyton sp., and Epidermophyton sp.  Those dermatophyetes developed a peculiar appetite on particularly keratinoid tissue, that is why they infect kerotinised palm skin, hair, scalp and finger-nails and toe-nails.

There are other molds that can cause coetaneous  skin infections, but will appear on other skin locations as well.

 Localized application of funicidial ointment or cream to suppress dermatophytes can’t penetrate deep enough and long eough to kill them. And biocidal chemical solutions such as 3% peroxide acetate, however, will burn all the applied areas, including normal tissues.

 Antifungal drugs (orally taken) such as Amphotericin-B and Ketoconazlole, will have some sort of side effects, such as liver toxicity, if taken orally. A lengthy use of anitfungal drug in combination of wrapped enclosing application of ectopical antifungals will suppress and eventually kill those tough dermatophytes.

 

 
(Left)  Palm and fingers infected by dermatophyte molds (superficial infection) with typical symptom of small blisters around infected areas and continous scarring and cracking of kerotinoid epidermis. Local application of antifungal cream and biocidal 3% peroxide acetate solutions sheded many layers of skin, yet they did NOT cure the hand, recurrence is consistent for 6 months.
 
(Right) One of the dermatophyte mold -Microsporium micrograph.