I ve had what feels like fluid behind my right ear and post nasal drip at times on the same side since having several cavities filled on the right side of my mouth almost two months ago. I followed up with the dentist about three weeks after the dental work because my back right lower molar was still very tender and they filed down the filling some. My tooth is still mildly sore at times but for the most part fine. The feeling of fluid behind my ear and the off and on post nasal drip hasn t cleared up. Advice?