I, too, think that he may be acting like this because he hasn't been feeling this good in a while, plus the cruddy weather makes 'em more hyper, and he might be lacking some ground manners.
Um...I guess I'd say to try working some ground manner exercises into the lessons. Simple walk-halt, halt-walk tansitions as well as turning and backing up (this has worked miracle for my super-pushy TB mare).
I can totally sympathize with the weather equaling a hyper horse thing! I live in the UP of Michigan, and when the weather gets bad, my Arab/App mare tends to totally lose it! The storm we (apparently you did, too) had this past weekend made her totally come unhinged. She attacked our dog (who is normally her very BEST buddy), attempted to buck me off numerous times, and was simply a total and complete brat.
He might benefit from some extra exercise, like lunging, or something before you ride along with some ground work. That way he can burn off energy on the line, but also get control of himself and start to think.
That's all I've got...
I hope he goes back to normal soon! =)