Jan, I noticed you didn't mention Oxcarbazepine (Trileptal). My 6 year old daughter has been taking that since she was diagnosed at 4 weeks old, and it has made a marked improvement on her condition. It is also a sodium channel blocker typically used to treat seizure disorders. While it doesn't completely stop her from cramping, it really lowers the amount she has on a daily basis. And, in the few times she's been too sick to keep her pills down, I've seen a huge jump in her cramps. This has also happened when we have forgotten a dose.
Do you have any experience with this drug? My daughter's neurologist prescribed it since she was so very young and it has very little side effects.