Your episode is very much like what happened to a student of mine two months ago. There is a fluke occurrence that can happen to colder water divers with hoods.
When you submerge, if one ear stays briefly dry, while the other gets a dollop of cold water right down the ear canal, you essentially are giving yourself what neurologists call a "cold water caloric test". This is a Neuro test that will elicit signs valuable in diagnosis, but which also instantly induces severe vertigo, due to the differential brain input from each ear, where the balance organs live.
My student had incapacitating vertigo, and could only shut his eyes to minimize symptoms. It's not just dizziness, but an intense disorientation that overwhelms most other brain input. In his case, he kept it together long enough to add a puff of air to his bcd at 10 feet, which he knew would carry him to the surface. He could not tell which way was up. He became nauseated.
In your case, I'd suggest that perhaps rather than memory loss, your senses were overloaded to the point where not much else on the dive even imprinted.
Once out of the water, symptoms largely subside, and on the next dive, your ears got their cold water exposure simultaneously. Hence, no recurrence.
Diving Doc
When you submerge, if one ear stays briefly dry, while the other gets a dollop of cold water right down the ear canal, you essentially are giving yourself what neurologists call a "cold water caloric test". This is a Neuro test that will elicit signs valuable in diagnosis, but which also instantly induces severe vertigo, due to the differential brain input from each ear, where the balance organs live.
My student had incapacitating vertigo, and could only shut his eyes to minimize symptoms. It's not just dizziness, but an intense disorientation that overwhelms most other brain input. In his case, he kept it together long enough to add a puff of air to his bcd at 10 feet, which he knew would carry him to the surface. He could not tell which way was up. He became nauseated.
In your case, I'd suggest that perhaps rather than memory loss, your senses were overloaded to the point where not much else on the dive even imprinted.
Once out of the water, symptoms largely subside, and on the next dive, your ears got their cold water exposure simultaneously. Hence, no recurrence.
Diving Doc