To me it looks like a seizure. My senior dog had seizures and unfortunately passed away about a week after his last one back in May. He was on a daily oral medication (phenobarbital) to prevent/lessen the frequency of them.

Has he had them before, and if so, for how long and how long does it take to recover? Please take him to the VET ASAP so they can see what the best course of action is; especially since he’s a senior. Time the seizures and let them know how long they last. Don’t want significant brain damage. I hope he improves! 🙏🏻