From the past two weeks, i have noticed that the far back side of my tongue has started developing a thick white coat which i am unable to scrape off. it was never like that; just one stroke of the tongue scraper i use was enough to make my tongue perfect

White material: The fact that you were able to completely remove this material by scraping it makes it likely that this is benign coating of the tongue rather than leukoplakia which requires evaluation. If you have further concerns,however, an Otolaryngologist is best qualified to evaluate,advise you and treat tongue abnormalities.

May be yeast: See your physiciasn to help clarify the diagnosis and why you have it.

Probably a fungal : infection. See an MD, confirm fungal infection and get antifungal medicine for it. More importantly need to look into why this happened -- typically seen in an immunocompromised host

Probably normal: If the whitish area is symmetrical stippled without clear edges and just on tongue then it's normal & may be due to irritation caused when you scrape.tongue. If there are pure white patches that are well demarcated irregular not just on tongue that's Leukoplakia, and may be related to tobacco use (chew or smoke) but should be seen by a doctor. Thrush would appear as tiny white dots all over mouth