I had this experience almost exactly with my first yorkie. The pneumonia and then sneezing-I think it was just irritation of the throat and nasal lining. I had him to the vet 3 times in a week to try to figure this out. He was eating, drinking, and playing well. Finally after all meds were done-he just stopped sneezing gradually. It took a long time though-like 2-3 weeks. And he hasn't done it since-for over a month. But it was hard. Hang in there
!!