An elderly lady, four weeks after discharging from respite care developed a very itchy, widespread, erythematous, vesicular rash. On examination, it was found as a small, grayish, serpiginous, linear lesion with a minute black speck at the closed end, in an interdigital web space. What could be the most probable diagnosis for this condition?

* This image based case is from Docplexus editorial team for educative purpose only. Source: Haymarket