Hi and welcome
! Congrats on your new yorkie, he sounds like a sweetheart!
On one hand, it's so very sweet that he adores your big dog - but if it tends to annoy the bigger guy after a while, I can see where that could be a problem. Does he like any certain toys or anything like that? Distracting him may help - ie, whenever he's hovering around the big dog, redirect him to something else.
Do you think he's scared...as in, does he shake or get nervous if the big dog isn't near him? If so, you could try a Thundershirt or a DAP Collar.
I'm sure the behaviorist will have some great ideas, so please let us know what they say!