I am sorry to hear that you have the sensation that there is something in your throat that will not clear, even when you cough up mucous, and that it has you worried. You ask some very good questions whether acid reflux
may be contributing, or making this sensation worse in your throat. I am going to recommend that you visit an ENT (Ear Nose Throat) physician to get checked out. They will be able to take a thorough history, do a complete exam, and maybe even examine your voice box using a flexible laryngoscope (a small fiber-optic scope passed through your nose to visualize your vocal folds). It sounds like you may be suffering from globus (the medical term for the feeling like there is a 'lump' in your throat, despite the fact that there isn't anything there). Often times globus can be caused by laryngopharyngeal reflux, where acid is refluxed up from the stomach and makes it up to the larynx and irritates the mucosa of the voice box. This makes the throat hypersensitive, and normal mucous that is present is interpreted as abnormal, and the person constantly has the feeling that they need to clear their throat. This can usually be treated with reflux medications, albeit it may take at least a month to notice any improvement. The ENT will be able to tell you if they think this might be going on.