Thank you for posting your query at DoctorSpring.com
I can understand your problem
You are suffering from sinusitis. Completed course of antibiotics again developed similar symptoms.
First we need to confirm that you have sinusitis. For that you can do one CT scan of paranasal sinuses. This can confirm sinusitis, can quantify it and can find anatomical factors responsible for it.
Usually we can take antibiotics for almost 3 weeks. You can start augmentin ( amoxicillin. Clavulanic acid) 625 mg two times .
Hope this helps
Feel free to discuss further,