Hope that everything goes well. A chiropractor may be able to help with a pinched nerve that could be simulating a pain similar to a sinus problem in that area. I wouldn't know why the antibiotics would help with the pain though unless its a placebo effect. Most important is that it seems to be helping.
I appreciate your response. I have gone to primary care physician several times during this entire sequence. I have also been checked out by a second ent physician. I have (since the post) gone back to the second dentist I saw who x-rayed extensively and feels everything with the teeth is OK. I have now gone to a third chiropracter who actually seems to be helping the headaches for now. I will try this for awhile. Thanks.
Has the root canals helped at all with the pain? How long has it been since the last root canal?
As for trigeminal neuralgia, usually the pain is associated not with a sharp stabbing or throbbing pain but its usually an electrical shock pain that travels on the face and is triggered by a trigger point or spot. There is refractory period in which after you trigger the pain, you can't restimulate the trigger spot and induce the pain again. That's how trigeminal neuralgia is diagnosed as far as I understand it.
As for a possible diagnosis to your situation, do you have pain when you move your head up and down. Have you had any sinus problems lately or allergies? Sometimes a sinus infection can feel like tooth pain. The x-rays will sometimes show what we call a cloudy sinus in which the sinus, instead of being clear and black on the x-ray, has a white hazy appearance indicating fluid buildup in the area. The antibiotics may help with the pain because the antibiotics are clearing up your sinus infection only to return later after the antibiotics are done.
You may want to check with your primary care physician or an ENT (ear nose throat). You may also want to post in the ENT section if these symptoms I described sound like yours.