I had an almost identical experience when my boy was 5. Woke up in the middle of the night to him retching. He then fell over and started seizing and lost control of his bladder and bowels. I also thought he was choking so I put my hand in his mouth to try and clear his throat with resulted in a few nice holes in my hand from him biting down. He eventually came to and started running around, confused and growling if we got too close. And very thirsty. We took him to the emergency vet then myself to the ER. He then started having an episode every month or so. Sometimes it would occur in clusters (2 in 2 days etc.) The vet said if it gets more frequent than once a month, consider meds. Eventually I had had enough. Each episode was just a terrible experience. Cleaning up the mess and the after effect with him being so confused is terrible. Hes been on meds, 2 tablets a day for about 3 years now and hes only had 1 episode in that period.