You seem to be suffering from acute sinusitis
and having post nasal drip
Since most of the sinusitis cases are viral in nature you require regular steam inhalation three times a day with warm saline gargles twice a day.
Avoid taking chilled and cold
drinks and take more of hot liquids like tea and soup.
Antibiotics are required in only 1% cases of sinusitis.
Take these measures for 2 weeks,you should be alright.
If symptoms persist then consult your doctor and get the prescription for appropriate antibiotics.