Not sure what caused it.
No one really ever told me what may have caused it .
In my case may have been work related.
Used to do commercial refrigeration.
Lots of big noisy compressors, fans.
Also used a lot of noisy tools.
To be honest no one really seemed to care.
The last ENT I went to wanted me to go to a different doctor for maybe an MRI.
I never followed up.
I don’t know maybe I will one day.