Hi D.,
I hope you find a solution other than surgery. We're going through the same thing with our Yorkie, which is common to their breed also. His knee seems to slip out once a month, he becomes completely inactive for 2 days (to the point of dehydrating himself on purpose so he doesn't need to get up to go to the bathroom), then by day 3 he starts getting around and by day 5 he's 100% again. Our vet recommended anti-inflammatories as a maintenance, or surgery if it continues. We are not ready to commit to the surgery quite yet, but since he's only 2 years old it looks as though this problem will not be going away on it's own. I would be interested to know how your second vet appt goes.
Good luck, and I hope your little one feels some relief soon!
D.