Hyperactive Thyroid - rare but could it be?

Eddy only had one blood test done to determine his Kidney Disease and the result weren't off the scale but I have heard that they can fluctuate.

Thing is, he's not good at the moment, he's hungry 100% of the time and cries and cries, after a few meals he'll finally shut up but he's not gaining any weight despite eating so much. He has got more picky about what he eats, but still has a huge appetite.
He's also hyperactive, he never seems to sleep - he's always up and always barking or whingeing and I try everything but he just won't shut up or lay down.
I also read that excessive drinking and urination is a sign of hyperactive thyroid.
He's also been doing this strange fitting thing where his body judders - it can be while he's standing, laying down, sitting - anything, his whole body shakes and it stops as soon as it starts.

Is excessively hungry a sign of it? Could it be that we missed a thyroid problem on the blood test and in actual fact, it's not KD? It's just that I'm sure they're supposed to lose their appetite with KD!

I'm thinking of getting him back to the vet to repeat the blood test.