My first guess is nutrition and a possible mineral imbalance. Are you getting enough calcium, magnesium, and potassium in your diet?
Green vegetables and nuts are good sources of magnesium.
Beans, nuts, figs, and milk are good sources of calcium.
Milk, yogurt, potatoes, and bananas are good sources of potassium.
I'm not a big fan of supplements, but if you don't have a good varied diet then you may need to use supplements.