Current symptoms:

Easily mildly nauseous even without apparent external stimulus. Can last for a few minutes to an hour, or more. Easily nauseated by car rides, was not a problem prior to BPPV. This one can last for an hour, often more. It's mild though. Never vomited before.

Sometimes I also get rapid shaking vision , like the world is shaking rapidly horizontally. This is also coupled with the sensation where I feel I'm falling backwards continuously. I've checked for nystagmus during these episodes, none visible to the eye. I don't really feel nausea either. These episodes come every few weeks , or even every few days. I don't seem to be doing anything that commonly induces them. They last for a few minutes.

Past Medical History: In September 2018 I hit the bottom back of my head during Aikido training. A few days later I started to feel like I was in a boat, swaying from side to side slowly. Upon medical examination I had a normal steady gait, no nystagmus, no nausea nor vomiting. Normal motor function, normal GCS etc and I also didn't show symptoms when performed the BPPV maneuver. As I have a history of Neurofibromatosis (NF1) and leukemia (ALL), they were concerned about a nerve pressed in my brain or a potential tumor. And MRI was done and nothing significant was found. I was informed that these sediments, otoconia, was the cause of the swaying and would go away in a few weeks. They did not.

Are my symptoms normal and what do they indicate? Can BPPV symptoms last for so long? Are they even correlated? Is there a possible cause?