Do you think it's okay to take a day off work because of pre-menstrual cramps?

I never usually do this kind of thing, but I called in sick today because when I got up this morning I could barely move, and I was literally slouched over in pain for an hour. I couldn't get up to take a shower or get dressed. I had to call in and say I was sick. The pain has only just completely gone now - it's usually not this bad and can be relieved by taking a couple of headache pills. I have barely taken a sick day since I started this job, but I feel so guilty about it - it seems like the kind of thing my male boss would sneer over, not that I'm planning on telling him. Do you think this was okay?