Hi, I have had severe episodes of vertigo and dizziness for 10 years along with many other chronic medical problems do to elemental mercury toxicity poisoning by inhalation while working at a biotech company in 2010. I even get dizzy when standing by an elevator or a large copier. I have had multiple vestibular therapy sessions with no success. After 10 years of these episodes, I was finally diagnosed with multiple sclerosis. Not one time in the 10 years that I Googled things for vertigo did I ever look at symptoms for MS, because I am not in a wheelchair? Request a Visual Evoked Potential test. The reason this test was done is because after my last mini stroke in August 2018 I started getting a silver and white print in the middle of my eyes that I cannot see through. It does not hurt. It is not like a migraine. It is called Central bilateral scotoma. Good luck.