My gyenocologist and I had a very similar conversation this week. She says that recent studies are showing that Vitamin D3 is becoming quite the talk for a lot of neuro-muscular troubles, and especially as an important possible treatment for fibromyalgia.

When I told her about my calves cramping all the time she suggested trying more Vitamin D3. The normal recommendation currently is 1000 units daily, but she suggested going as high as 2000. Toxic at 10,000 so don't overdo it!

Everyone else here made very good points, and if you are working out a lot the sodium will be very important to replace.

I have the same symptoms you do, and have tried all that you have.

tonic water is horrible.
ZEN: You are doing it wrong... add the gin and limes!

Good luck and let us know if you figure something out.
Jes