IMO excessive throat clearing means sinus infection draining into your throat, or a lung infection that forces excessive phlegm into your throat.
In either case I think that taking Colloidal Silver in a spray bottle or in a nebulizer to get CS into your lungs. I have used this procedure very effectively on many occasions. In a nebulizer, take CS 15 minutes 3 x daily. Orally take 3 tbsp spaced morning, noon & eve.