Possible seizure in 4 year old golden

My Golden Retriever, Milo, had a very concerning episode this afternoon that I would love some perspective on. Milo is 4 years old, 82 pounds, neutered, and very healthy-- he is up to date on all of his vaccines, eats and drinks normally, and is very active.

At around 2pm today he ran into my roommates bedroom seemingly disoriented. He tripped over some things in his room and ran into her desk and then fell to the ground. His running into her desk seemed to be due to his disorientation, not due to his tripping. He did not hit the desk hard, but bumped into seemingly due to disorientation. Immediately after falling (he was laying on his stomach,) he began to pant uncontrollably, drool uncontrollably, and his body tightened while his back legs sprawled out and trembled for about 2 minutes. He came out of the episode, tried to stand up, and had trouble bearing weight on his back legs, specifically his back right leg.

I was running home as this was happening and calling an uber to the emergency vet as I entered the apartment. He seemed anxious after the episode and he was anxious at the emergency vet (he is always anxious at the vet, however.) He was playful at the vet's office and was trying to play fetch with the door stopper in the exam room. The vet found nothing abnormal in any of his testing nor his bloodwork and believes he may have have a torn CCL and could have fainted. She does not suspect a seizure due to how alert he was.

My dog Milo, however, tried to play fetch immediately after I picked him up from his neutering appointment a few years ago. He once chipped his canine tooth while playing and did not react at all, but rather continued to play. Milo is quite stubborn and will play fetch in any circumstance. I have a hard time ruling out a seizure due to this.

Has anyone had any similar experiences to share? I am considering getting a second opinion, not sure if it is worth it? We currently reside in Brooklyn, NY.