A marvellous bi-product of the Icelandic fishing industry is the enzyme trypsin that we humans also produce but not as efficiently as the clever cod.  It has antifungal, antibacterial, antiviral & anti-inflammatory properties and no known side effects.  It is colouless, odourless, tastes sweet, and apart from an infinitessimal amount of harmless preservative is completely natural.  Using it on toenails usually sorts out fungal infections in a very short space of time.  Infections in the extremities of the body suggests that the immune system is energetically low, and so a general check up and a hefty immune systemic boost are called for.  This can be effected by your favoured style of medication (eg: allopathic, homeopathy, flower & gem essences, & so on), bioresonance or spiritual healing, &c.  And don't expect your son to toe the line until he's cured!