Im 23, male, 5'11", 188 lbs, and have been having this lingering headache for a little while now. Probably a week or 2 on and off. Behind my right eye going straight back to the back of my head. Now its not horrible, its tolerable but it's there. Not sure what the scoop is. I personally think its from lost sleep. I don't always sleep that good. My diet isn't the greatest but lately have been eating a lot smaller portions through out the day. Anyone help me out?

When you said that it is behind your eye that made me think... do you have glasses? Have you got you eyes checked lately?
My optometrist said headaches in the eyes usually means you may need glasses or if you already have glasses you may need your prescription updated.
Another thing you said is a not so good diet... how much water do you drink? You should be getting 8 glasses a day. Many headaches are due to dehidration. Usually when I have a headache I just drink a glass of water or two and it is soon gone. That's without a tylenol.

I haven't had my eyes checked lately but I do not have any issues seeing things. I could see water being the issue, I usually am eating salty foods and lately a lot of beer.

Ya, that could do it.