Shaking can also indicate pain... which is what he'd be feeling if he ate the wrong food causing pancreatitis, or if your friend gives her dog rawhide chew toys and he got a piece and it got stuck somewhere between his mouth and his butt. I would call the friend to find out exactly what he could have gotten hold of, or into (other dog's food). Yorkies are very delicate creatures, and just being away from their Mom can cause enough stress to cause a medical problem/emergency. I'll keep Little DJ and you in my prayers...
Looking forward to your update... please...