I was saved from a similar problem with an old maid's remedy. of all things. I had irritating phlegm or something in my throat all the time. I was constantly clearing my throat and driving DW and friends nuts. I saw GPs and ENTs to no avail. Most of them though it was postnasal drip from allergies but none of the pills or inhalants did much. The ENT showed me how my vocal cords were getting degraded and cautioned me that I really need to stop clearing my throat. Thanks a lot - as if you can just ignore an irritating bolus of crap in your throat.
Finally, in some obscure corner of the interwebs, I discovered references to Bragg's Apple Cider Vinegar 'With the Mother.' When I googled that I discovered a vast cult of fans. It would allegedly cure virtually anything but, to the point, lots of the saved had my problem. What the hell, why not. Within days, my problem was solved. No more phlegm, no more throat clearing. That was about 15 years ago.
The formula is simple, take a tablespoon or so daily. Most people mix it with water or juice. I just take a sip from the bottle, hold it in my mouth behind my teeth until I can bring a glass of water up and then slam it down. According to all the reports, it is essential that you use vinegar with "the mother," which is some sort of cloudy residue from the yeast that turned the juice to vinegar. I also discovered just this year that you should refrigerate the stuff after opening. For years, I left it out on the counter like any old vinegar, but it gradually gets stale tasting. I didn't pay much attention since all I ever did was slam a tablespoon down. No salad dressings or marinades. When I read that it should be refrigerated (and low and behold, it is right on the bottle) I discovered that it retains a much nicer fruity taste. The effectiveness was unaffected by my lack of refrigeration. I have stopped taking it briefly while on vacation or when I run out and everything is fine for a while but eventually the phlegm returns.
This stuff really is a miracle cure, or has a powerful placebo effect, I don't much care. It works for me. Try it, you will like it. And you readers without phlegm problems should google it too. It solves all sorts of obscure stuff, maybe it's the universal placebo.