Thanks for asking.
Based on your query, my opinion is as follows.
1. Due to sinusitis
, you have headaches
2. Due to post nasal trip, you are having chronic irritation and cough
3. Due to inflammation in pharynx, difficulty in swallowing is present.
4. You need antibiotics, antihistamine and steam inhalation. Meet your doctor.
Any further queries, happy to help again.