I Get Dizzy When I Shake My Head Back And

I get dizzy when I shake my head back and forth from side to side - in sitting or standing position - feels like fluids moving around in my head - "swimming" feeling.....and I get nausea at the same time every day - around 5pm. I have a great deal of phlegm each morning and I think the PND might cause the nausea - and just recently started with burning sensation in my esophagus at random times during the day