What Causes Itchy Penis With White Discolouration On It?

Hi..I'm 18 years old & I seem to have a severe problem .Several times a day (specially at night , while or before sleeping ) I have a severe itching sensation at the tip of my penis (not inside the skin, just on the outer side i.e. the skin around penis) .And I can see some kind of white layer getting formed at the tip of the penis I masturbate around 4 times or sometimes 5-6 times a week Tell me what I can do to get rid of this bcoz It itches so much sometimes that I can't even sleep !!!And if u prescribe sum medicine consider its availability in INDIA !!!