I get a 'burning' feeling in the back of my throat and then major draining of phlegm with a chunk of solid material in it..why?

Probable nasopharyng: The nasopharynx is the area at the junction of the nasal cavity and upper throat which can have both acute and chronic infection. The acute type has a sore throat, drainage, and often ear pain and can be viral or bacterial. The chronic form has chunks of discolored drainage particularly in the morning with persistent daytime post nasal drip and sore throat. Suggest bacterial culture.