DW got it prior to heading north while we were in Harlingen for a week. Took her to a walk in clinic and she was diagnosed with sinus infection and bronchitis. He gave her 10 days of augmenton, an antibiotic. Note no 3 or 4 day "z" pack was prescribed.
IMO, the cause is the burning of the sugar cane fields. When we were in Mission I couldn't figure out why my neighbors park model had a black roof like mold was growing on it since it was in sunlight with no shade. Both DW and myself felt plugged up while there. When we went to the Gulf and got some salt air in our lungs it went away. Our northern upper respiratory just ain't use to that stuff is my guess.