Thanks for writing to H.C.M. for your query.
I have gone through your query regarding sudden blockade in left ear, your ent doctor has examine you and said nothing is there therefore I suppose that your external ear is o.k. thus now problem is either in middle ear or it is in the internal ear.
Usually in middle ear blockade patient observes echo of his own spoken words while in cases of blockade from internal ear no echo is heard on patient's own spoken words and the external sound is percieve very feeble. Clinically also middle and inner ear
involvement can be differentiated, but for confirmation one should believe in audiometeric testing.
For management you are advice these investigations.-
(1) Audiometery ( Pure tone & Impedance ).
(2) C.T.scan of paranasal sinuses
(3) Blood sugar - F. & P.P.
A tharough clinical examination and co-relation with inferences of above investigatins will tell about diagnosis which than accordingly manage.