Most likely the first round of antibiotic did not completely clear the infection and it raised it's ugly head again. Back in the spring when I had bronchitis I had to take 2 rounds of Zmax before the infection was cleared.

We have more and more drug resistant bacteria these days.

Have you taken an anahistamine to help clear any allergy you might have along with the infection? Zyrtec or Allegra are good but do require prescription.