Greetings. From your history, Clearing throat and spitting mucus can be due to
1. Nasal allergy
2. Sinus infection
3. Acidity
From the CT scan provided, the sinuses look clear. But features of nasal allergy is also there.
Next Steps
consult online/directly if possible for
1. treating nasal allergy
2. evaluating for acidity
Health Tips
avoid chilled / oily spicy food items