I have fibromyalgia, and at night after I sit down for a while, I get the worst muscle cramps in both legs, especially in my thighs, and my right thigh is the worst. I can actually see the muscles twitch. I am already on a postassium supplement, so I know it s not that. I have tried the heating pad, but it helps only a little bit. Is there anything else I can do, or is there a vitamin or supplement that can help me? Thank You for your time.