Thanks for contacting HCM I am sorry to hear that you have been having persistent sinus headaches. You doctor has already taken x rays of your sinuses and found no infection. Your doctor then went ahead and prescribed an antihistamine and a course of antibiotics and I assume you continue to have headaches. In my clinic I see people who have been diagnosed with sinus headaches for years and no documented abnormal Sinus x rays or CT scans. I then question whether they actually had sinus problems in the first place. Typically people with migraine headaches will complain of sinus congestion and pain. If these headaches cause you to stop what you are doing and lose work or time with family then you more then likely have migraine headaches. For this I usually recommend taking a triptan medication like Imitrex to help abort the headache. Another frequent cause of sinus headaches is TMJ or temporal mandibular joint syndrome. This headache or facial pain starting in the and around the jaw that can radiate into you head and sinus areas. This is frequently associated with a clicking or popping at the TMJ. For this I recommend an anti-inflammatory like Naprosyn and possible dental referral for a bite guard. At this time I would not recommend taking a CT scan since your initial X rays have been negative. I would ask your doctor if any of the above problems could possible cause your headaches. Hope I answered your question. Please contact us again with your medical concerns.