nail separating for finger

Thum nail is separating at end of thum. No injury or discoloration.

[Dr_Aparna]

Hi,
It could be a fungal infection of the nail.People who sweat profusely are prone to many types of fungal infections. That's because fungi thrive in warm, moist environments such as sweaty shoes. That's also why you're more likely to get an infection in your toenail than in your fingernail. A nail infection usually begins as a white or yellow spot under the tip of your nail. As the fungal infection spreads deeper, your nail may discolor, thicken and develop crumbling edges. Sometimes your nail may separate from the nail bed, and the skin around it may become red and swollen.
Anti-fungal ointments like Econazole (Spectazole) or Oxiconazole (Oxistat) may be applied to it.
Or it could also be psoriasis of the nail.Fingernails and toenails are frequently affected, called (psoriatic nail dystrophy).The disorder is a chronic recurring condition.
Ointment and creams containing coal tar, dithranol (anthralin), corticosteroids like desoximetasone (Topicort), vitamin D3 analogues (for example, calcipotriol), and retinoids can be used on the affected areas.
ref: http://en.wikipedia.org/wiki/Psoriasis