This is Dr. David
I am sorry you are having these pains.
you could be suffering from sinus inflammation or bacterial sinus infection causing these headaches.
you may need more allergy medications if the flonase is not enough
signs of sinus infection can be runny nose, sinus pressure, stuffiness, difficulty breathing, headaches, sinus tenderness when you press on the cheeks or forehead between the eyes. those are where your frontal sinuses are.
you may benefit from taking allegra 180mg daily or claritin or zyrtec.
the Flonase can take several days to start working to help decrease sinus inflammation.
bad sinus infections can require a course of antibiotics for treatment as well.
you could be having migraine headaches as well, or dehydration, or caffeine withdraw headaches.
let me know if you have other questions.