This has been a hallmark symptom over the years for me. It doesn't happen often, maybe 2 or 3 times a year. Different levels of severity, sometimes associated with higher levels of fatigue sometimes not. I haven't been as diligent at keeping notes as I should but pretty sure I can associated it with blisters on the roof of my mouth and on my gums. But had it since the beginning. Pain would be similar to sciatica, and as mentioned it migrates around my head the same way sciatica might start on your but cheeks but at some point end up in your feet. I've heard people talk about facial palsy and lyme, but from the reading I have done that is more to do with paralysis. Which I don't think is an issue with me. I also got to thinking couldn't researchers take a swab of a blister and figure out which virus is driving it. I presume there are a few like hpv and herpes that might be associated with this? Than you have canker sores associated with immune disorders. I remember reading you can get hpv in your throat and it puts you at a higher risk of throat cancer. If it could do this is it much of a stretch to assume it might damage a vital nerve in your head somewhere? Has anyone ever did any serious research to rule this out? Might there be a way to focus antiviral treatments in this area? Say an injection?