I'm glad that at least there is a diagnosis, and maybe with some time and thought, you might be able to come up with some reason that triggered it.

However, hope it won't happen, isn't safe !
Won't you please consider "some" head protection. If a Helmet is to obtrusive, maybe one of those Head Bands would work. Some of those are kinda thick, and would give you some protection and not look so bad...

Please, don't just trust this to luck.

I would at least discuss Aspirin Therapy, or possibly a BP reducing medication with your Physician.