I believe that my migraines are a form of allergic reaction and find benedryl tablets helpful when I'm fighting a migraine. Sinus pressure/pain is an indicator that I'm reacting to something.

I’m with you, when the pollen is high, my head hurts & I can’t figure out if it’s migraine or sinus. I usually treat as sinus take my Sudafed and nasal spray. If doesn’t clear in a few hours I hit the Maxalt & Nurtec for migraine.