There is some kind of medication that I was prescribed for cramps once... hang on....
ok, found it, it's called celebrex. It's the same type of medication as ibuprofen, but meant specifically for cramps. If you take it right away, it works really really well.
With any medication, if you anticipate your cramps and start the medication before the cramps start, that will work the best. For example, if you expect your period to start on Monday, and you usually get cramps as soon as you get your period, take a dose of medicine as soon as you wake up on Monday, even if you don't have cramps yet. And keep taking it until you are done with your period, or the time you usually have cramps. Take it every 6 hours or however often you are supposed to.
Some types of birth control might work better than others for you, so you might want to switch to something else if it's not helping at all.