It could be to do with anxiety, or otherwise psychological...

Or it could be neurological.

I had some experiences... And I got referred to neurology... And they asked me some questions... And referred me to clinical psychology for breathing training / anxiety management.

Sometimes things can be caused by a neurological lesion, or something, so some kind of brain seizure. I don't know how to tell the difference... But a neurologist should be able to figure that out.

:-)