One month ago after traveling with plane, I started having sore, scratchy throat and hoarseness of voice. No fever. After a couple of days, I took z-pack. Symptoms improved but did not disappear. 3-4 days after completing treatment, soreness returned. At ER, augmenting was prescribed. MD said there was a little redness, rapid strep test was be negative. Symptoms improved in th e next two weeks, soreness disappeared, hoarseness improved but not completely. Today, soreness returned. What is it?