Hi Dear . As per your query you have sore throat and doctor has prescribed Z-pac . Well there can be many reasons for sore throat like bacterial and viral infection or in acid reflux . But in your case it seems to me that sore throat is probably because of viral infection , which usually go away by its own after completing the course . I would suggest you to consult ENT specialist gain for proper examination . Doctor may order test like throat swab test , viral culture test and blood test to confirm the diagnosis . Doctor may prescribe antiviral drug like acyclovir and with anti inflammatory . For now do warm saline gargles , take over the counter cough syrup and take ibuprofen or acetaminophen for pain and swelling . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari