I'm a bit late here, but I am wondering if you've considered the possibility that your sinus headaches are actually migraines? The two are often confused becaus

I'm a bit late here, but I am wondering if you've considered the possibility that your sinus headaches are actually migraines? The two are often confused because they present similarly, and it is believed amongst headache and migraine experts that most so-called sinus headaches are actually migraines. It would explain the MSG trigger, too.