I think it is the (new) hat. It's a small, comfy, very nice hat, but, it is low in profile, and therefore pulls my hair back just a bit, so with the constant pressure/tension on my bangs, it gives me a headache. Just now, I decided to keep the hat off when I am in the house (similar to how I treated my last cadet hat) and just wear the thing when I am out and about. This is a good method to hat wearing.
Now, the headache seems to be subsiding, a very good thing. And also (non-headache related), I had a veggie/quinoa meal for dinner (wraps with mayo), and it definitely hit the spot.