Suggest Treatment For Accumulation Of Mucus In Throat

I often get an accumulation of mucus running down my throat causing me to have coughing fits. I tried taking nasal pumps, neti pot, antihistamines, etc - nothing works. When I have these coughing fits, I get really warm. Sometimes they even make me throw up a bit. I have been dealing with this for over 2 years and keep hoping I will find a solution to my problem. It doesn t seem to be a seasonal thing as I have it all year round. Sometimes I just start coughing, not knowing why but some triggers are: coffee, tea, chocolate, toothpaste, strong smells of perfume or chemicals or even grass cutting. I have had chest x-rays, sinus x-rays, ears checked, asthma tests, etc everything came out clear. I know that it s definitely something that has to due with postnasal drip, as I feel it running down my throat and try as much to spit it out when it happens. I would be so very grateful for any help or advice. Many thanks! :)