What Causes Cough,congestion And Crusty Blister Like Appearance In Corners Of Mouth?

On Saturday, as I was returning from a week in French Polynesia, I first started sneezing, then got congested and began coughing. I also noted redness and pain in the corners of my mouth, mostly on the upper lip, just above the crease where the lips meet. This worsened for a couple of days and became somewhat blistered,and then a little bit crusty in appearance. I determined that I was developing my annual bout of bronchitis, which I have had many, many times, over the years. I began applying Neosporin to the corners of my mouth and seem to be getting some relief I comme3nced a ten days' course of Amoxicilin 500 mg bid on Monday morning. I am most concerned about the mouth sores. Suggestions. My only allergy is to Cephlex.