i'm pretty sure the shaking and shivering is excitment. Layla shakes when she gets excited and just doesn't know what to do with herself
as long as his gums are pink and he has food/water down i'm sure it is excitment - he is still pretty young. Layla is 2.5 and the "excitment" goes away
she is very excited to see me stil but isnt shaking like she did when she was younger. Do you walk him before you leave and when you get back? Is there someone who can maybe come for an hour to let him out? I'm sure he is fine during the day (Many yorkies here are alone during the day and do great) but it might help make you feel better.