Pain in the Head

For the past few weeks, I have been getting headaches consistently in the afternoons, between 3 and 5 pm. They aren't migraines and they aren't particularly debilitating, but they are annoying. I am starting to suspect that they may be caffeine-related. If I have 2-3 cups of coffee in the morning, I don't get a headache. If I have less, my head hurts and then it's too late to remedy altogether with a diet coke. This is bothersome to me for at least 2 reasons. 1) It's a pain in the ass (and head) to get headaches. 2) I love caffeine and I don't like that something I love would hurt me just because I didn't consume enough. It wouldn't be very nice for your good friend to hit you over the head just because you couldn't hang out with her for the morning, right, right? Addiction sucks, man.