What Causes Small Black Patches On Upper Part Of Tongue?

 I'm 19 and I'm from Andhra Pradesh, India. I have small black patches on the upper part of my tongue, specially on the tip. I have around 5 of them, which I badly want to disappear. I've tried various home remedies like applying lemon juice and pineapple juice, started drinking more amount of eater every day, none of which worked. I'm afraid of laser and other such operations. Kindly suggest something that wouldn't hurt my tongue but would give me drastic results. Like an ointment. Thank you sir/ma'am. :)