excessive phlem and white particles in my throat

i am seventy nine years old, in good health, 5'6" weygh 200 lbs. am consantly coughing up clear or amber colored phlem and/or white or brownish colored particles caising a running nose requiring a handkerchief
at most embarasing times. the condition surfaces almost everytime i eat a meal. i am desperately looking for an answer. i have been to an ent who really didn't care, gave me a placido scripy and sent me on my way. i have had this condition for four years