I cleaned out his hoof searching for a crooked nail or a foreign object that might have punctured his sole. I gently rotated his knee and fetlock - nothing. As I worked to find something to explain the lameness, other than a suspected abscess, Izzy nibbled my coat, snuffled my hair, and generally made a nuisance of himself. He wasn't in that much pain.
As of last night, he was perfectly sound at the walk, but he's still not quite right at the trot. Although truthfully, I couldn't get a good trot out as it's been windy and rainy, and Izzy doesn't really focus in those conditions.
I am 99.9% sure this was or is an abscess, but I wish it would hurry up and be gone. I have a class all day tomorrow, but on Sunday, I'll have time to work on getting a decent trot out or even a ride. That always tells me if he's sound or not.