Hi
Firstly stop panicking the symptoms you have along with the reports suggest you have a chronic sinusitis along with gastritis.
The constant post nasal dripping causes pain on that side of throat and if there is on going acute infection the pain radiated to that side of ear. You also have gastritis which causes reflux to throat causing constant pain in throat. This is very common seen in many individuals. Don’t google go by doctors suggestion.
Next Steps
Do steam inhalation daily twice for some time the change is noted gradually. You can consult online would suggest medications based on further questions.
Health Tips
This shall improve but nothing to panic avoid visiting too many doctors. Avoid spicy foods and eat regular meals.