Well felt rattling in my lungs today that was REALLY bothering me.. thought maybe it was because I went from toprol 100mg back down to 50mg.. they took an XRay and said I had acute Bronchitis.. I asked the DR could this have been the cause of my recent increase of PVC's and she said yes.. is this true? If so at least I know what has been wrong with me.. they put me on Zithromax (antibiotics) for the bronchitis and she said it should clear things up.. anyone ever have this happen to them or know anything about it? any help would be great!