I would think (just an opinion) that what you just described above sounds much more mellow that the crazies he had before the dose was lowered. This now may be normal morning zoomies etc. now that he feels better, and if his blood thyroid level was low and it's more where it should be now, he's more active. And it didn't continue for hours as before.but is it okay that he gets a little wired, or should he have no notable response to the med?
*Edited to add: I just went to find him after those zoomies, and found him laying on my bed, which made me feel better. That burst of energy didn't last long. That's better.
Moo does that bump in the tail thing when she's really playful and energetic, it's a positive thing to me. I also see it when kitties are doing the Kitty Crab Walk.
I'd expect to see a cat being more active (but not to the point of craziness) when on thyroid, if their blood level was low before.
The coughing- how often is it? Waffies did that the other day, I haven't seen that from Waffies before. But not since.
How's the itching and scratching with the lower dose?