Headache since October 2011 !

ive had a headache for about 3 1/2 months now. The symptoms of it are a constant dull ache around my temples and the top of my head, sometimes slight nausea but no vomiting. sounding blocked up, pain in jaw muscles and around general facial and head area. Applying good pressure to the jaw muscles for 20 seconds and then releasing the pressure relieves the headache for a few seconds. I have in the past had nasal discharge but not recently. I have had an MRI scan which shows very blocked maxillary and ethmoidal sinuses, yet i have taken a treatment of erithromycin and nasonex spray, and am now on a treatment of a sinus rinse, clarithromycin and a nasal steroid and my headache's dont seem to be going away.
If possible i will somehoe attatch these MRI images
HELP!