DMG, Your history is similar to mine which started 11 + years ago following sinus surgery in June 2014. Since then i have had many unsuccessful treatments and very few reliable diagnoses. I had gamma knife surgery to my right trigeminal nerve which did nothing. I spend 5 days as an inpatient at Jefferson Hospital in Philadelphia for an infusion of lidocaine. No help. I've had botox and nerve block injections and my current doctor wants me to have some more botox injections. I have had acupuncture, acupressure, message (Crainosacral, etc) and therapy with psychologists and psychiatrists. I have been to see specialists at the Univ. of Florida, Maryland, Virginia, and Colorado (where i am now in treatment). A neurosurgeon at Johns Hopkins advised that he did not consider that my conditions suggested that neurosurgery would help. Since i have a bulging disk at C 3-4 (asymtomatic) I did have steroid injections there. If only the sedation would have lasted longer, that might have helped, but alas, the pain was back in 20 minutes.
The most help i have found was from various pain mediation devices i use. Here's a list:
1. On an overnight train trip to New Orleans we thought to use blinder masks to help us sleep. That was my best night's sleep in years . I now use a sweat band on my head 95% of a 24 hour day. The light pressure around my head, with the band just above my eyes gives tangible relief and i wear one over my eyes to sleep at night.
2. I also find significant relief from using a "Migraine Cap" bought thru Amazon. When not on my head these caps are kept in the freezer. I have about 4 of those.
3. I have found that applying pressure to various places around my head gives relief. In my shop i have made wooden sticks of various lengths that i use to apply pressure around my temples, eyebrows, beneath my nose, my chin line, etc. I keep one of those sticks in the car.
4. Finally, i have recently started using a CPAP device to help with a sleep disorder. I find that the mask covering my nose and mouth does put pressure around my nose. That source of pressure provides some pain relief.

Currently i am optimistic that my current neurologist near Denver, Co. might help me. Her diagnosis is "Chronic Migraine Headache". I am now, once a month, injecting myself with Ajovy and i MUST keep that up for about 6 months before I can expect to detect any relief. I also have some pills of Ubrelvy to take in times when i sense an increase of the pain. Since the pain is constant it is difficult to know if it is getting worse or just the same old pain.
I also thank my wife and family for the support i have received from them. Don't know how we would get thru elusive recovery without them.
No doubt there are several misspellings in this too long reply. I hope some of these home remedies might help you. Your responses back to me are welcome.

WSC