As more than 9 years ,you had no problem, means the surgery was done correctly.
Now also, the problem is not affecting nose (no watering, no sneezing)....
It is most likely General flu like symptom.
Take anti-inflammatory medicine,
Plenty of fluids.
X3days.
Next Steps
If it recurs after stopping medicine, then ...
1)Sinus endoscopy
2)CBC.