I think it was the my contact lens that caused the headache today behind my right eye.
As I put in a different lens than the one I had been using...as that one had ended up getting a chunk taken out of it somehow...
So I put in an older lens...
And while at work ended up with a slight headache...that grew progressively worse until it was positively pounding behind my right eye.
There was a lot of relief after I took out the contact in that eye...
So I have to wonder if I accidentally grabbed a contact that was the old stronger prescription...As that's the only reason why I could think that it would show up behind that eye.

In any case I spent the day laid up on the couch with heat packs and taking Advil to make the headachce go away as a nap didn't help it at all.