Hi, I Have Been To Dr. Several Times Regarding Mucus

Hi, I have been to Dr. several times regarding mucus in my throat. I also have excessive cough. There is no nasal drip, only mucus and discomfort in throat which causes me to constantly try and clear my throat and spit it up but nothing comes up. I have been given antbiotics and it did not alleviate the problem. When I lie down or try to sleep, it feelsas if I'm suffocating. I have had this problem for about a year. Please give me advice