I have cramps very bad. :S I took alieve, and it is slightly better. It's so bad I can feel it it in my toes.
Did you take two of them?
If not, you might want to take another one. Also, don't be stoic with menstrual cramps because it's a lot easier to head them off before they get too severe than it is to get rid of them once they become bad.
Aleve helps my cramps but Tylenol doesn't do a thing for them. A heating pad also helps me. The medication that works best for me is Ponstel, but you can only get that with a prescription.