I Often Cough When Speaking. I Have Seen Docs ENT

I often cough when speaking. I have seen docs ENT - clear, pulmonary - clear, and lastly gastro doc did endocopy and stretched my upper esophagal sphincter a week ago, but no improvement. He said acid reflus not even bad enough to treat and he recommended I see an allergy doc. I fear I have terrible post nasal drip which gets worse when I speak and I do have a deviated septum. I cannot have a real conversation with anyone without coughing. I have given up all reflux causing foods, just in case. I also have meniere's disease and stage one multiple myeloma, so am really careful about everything I ingest. Any ideas?