Good afternoon, I do have some ideas for you. It sounds like you still think it might be dental related but I hear you saying that you have visited your dentist and your doctor. Did either doctor talk to you about grinding your teeth and using a mouth guard? The other issue that comes to mind is the fact that the doctor treated you for pain associated with a diagnosis of a sinus infection. It could be possible you have ongoing sinus issues and without further info I cannot evaluate that potential. However, check the status of your nares to see if they are clogged up during the day. If you notice trouble breathing out of your nose then working on your sinus problem would take care of your headaches. A sinus problem can be treated by seeing your doctor for allergy testing, a possible prescription for sinus congestion or the use of AYr, an over-the-counter saline mist. Good day sir and without further information, testing which actually should be done by your physician, I cannot thing of any other issues relative to your complaints. Thank you for using our service. Kathryn, MS,RDN