Rick,I am so very sorry for your loss. But may your parent's love live on in your memories and bring you peace.
"Almost everyone experiences a few seconds of spatial disorientation at some point. For example, when a person watches a 3-D movie in the theater and momentarily perceives an illusion of moving or falling as the images rush past.
However, frequent episodes of vertigo—whether lasting only for a few seconds or days on end—are a primary sign of a vestibular dysfunction, especially when linked to changes in head position. If you have vestibular dysfunction, it means there is a problem in your inner ear.
By contrast, dizziness can be a primary sign of a vestibular disorder in addition to a broad array of cardiovascular, neurological, metabolic, vision, and psychological problems.
It is also quite possible that a person may have a combination of problems." reference: vestibular disorders
And don't forget it is spring when many people suffer from allergies.
I would strongly suggest you see an ENT Dr. since all your cardiac tests are normal. Please remember I am not a Doctor nor do I play one on any television show.
Kindly,
Kitt