Help! there's white substance on back of tongue and i'm having sore throat symptoms?

This could be a: Viral infection, strep throat, yeast etc. Med eval would help to differentiate. For significant sore throat with swollen tonsils / lymph nodes – see physician ; get a strep throat test/ culture. If you have strep throat, antibiotic therapy is imperative to prevent future complications. Consider tylenol (acetaminophen) or nonsteroidal anti-inflammatory medications. Saltwater gargles: mix 1 tsp salt in 8 oz warm >.