Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
If you think that this is due to not exercising the calves enough, you could start running or do calves exercises followed by stretching ?For what it's worth, I've found that I get them less if I stretch out a little and massage the calf muscle a little before diving. For me, anyway, that seems to do more than anything I drink or eat.
I think finning/kicking "up/down" uses too much calf. If you press against the water similar to how you press against a bicycle peddle when you stand out of the seat (mountain biking uphill for instance).
That motion works very well to get a LOT of power into your fin without the "kicking" that taxes your calves.