welcome to healthcare magic,
as per the description of your symptoms,
it seems that you have been suffering from gastritis
caused by Azithromycin
the most common side effect caused by Azithromycin is acute gastritits
so, i advise you to take any antacid pill like PANTAPRAZOLE OR RABEPRAZOLE
, available through OTC.
if you havent get any relief from antacid pill , i advise you to consult a ENT specialist
hope this answer will help you..