Natural headache remedies?

I have had a headache for several days now. Not a migraine like I sometimes get, so I do not want to take medicine for it and build up an immunity for the times I really need it. At first, I thought it was dehydration, and drank a bunch of water, that did not work. I tried getting some extra sleep, but that did not work either. If I was stressed out and overwhelmed, I would find a way to relax, but I am not stressed right now. Any natural remedies that you know about that I could try.