Hello,
First and foremost thing is to know more about your history and diagnosis for what your treating consultant had started fluticasone nasal spray.
Another thing is Basically people with a history of recurrent polyps or allergic patients use these nasal sprays for a long time do not get any side effect of headache till now. Literature also donot shows any evidence for headache by this nasal spray.
So the thing u need to do is to get evaluate more further regarding your headache if it's persist from a long time.
Health Tips
Visit a nearby ENT consultant and get yourself examined thoroughly to evaluate a proper cause.