Hi,
IT could be a very mild case of Athlete' foot or Tinea pedis.It is a parasitic fungal infection of the epidermis of the human foot. The term "athlete's foot" refers to the disease and not the organism (fungus) that causes it. Several different fungi, called dermatophytes, can cause tinea pedis.
The fungal infection is often treated with topical antifungal agents, which can take the form of a spray, powder, cream, or gel.