I had tested COVID negative but I feel my throat sore and have post nasal drip. What can be done?

Hello doctor,

I had thyroid fever two years back and experienced similar discomfort; the doctor had prescribed Omeprazole. I have been experiencing a thick postnasal drip from the mid of this year, which makes me cough out so hard, but no phlegm has come out. I lost my sense of smell and taste when it began. Although I tested COVID negative, doctor had prescribed Amoxicillin and Clavulanic acid 625 mg tablet for seven days when it first started. Later I was adviced to take Azithromycin 250 mg (Azilex) for three days, Zincovit tablet one per day, Vitamin C and Zinc tablet with nasal drop Ephedrine. After three months, I was given Azithromycin 500 mg for three days, Decatylen Lozenges three times daily, and Koflet cough syrup. I have the sensation of a lump in my throat even with repeated swallowing of saliva. I always need to clear the throat to clear the phlegm in the throat almost every minute or two. I can feel phlegms in my chest and throat when breathing. I am currently experiencing very severe burning and tightness sensations in the throat. Sometimes, I have to stretch my neck to feel comfortable. I have sour taste and thick saliva. I have recently developed sharp or sudden chest pain. I experience this even though I drink a lot of water.

Please help.

Thank you.