Tazz breathing habits

From the first day I received Tazz, which was a couple of weeks before christmas Tazz seemed to have breathing problems. At any moment Tazz would sneeze for atleast 20 to 30 seconds and I didnt know what was going on. My boyfriend says that when he went to pick up the dog it was like 8 people at the kenel place smoking ciggarettes. He also said that they place smelled like a ciggarette farm and that the whole place smelled like smoke. Till this day my poor Tazz has breathing problems. Tazz stoped the sneezing, but he still does nit breath right and I hate it. Tazz is worst then a roc I once had who breathed very heavy. I dont know what I will do about it because the vet said it was normal and doctors really never know anything these days so who really knows?