Muscle cramps are probably because of electrolyte imbalances (low potassium/calcium/magnesium) and fatigue is probably due to iron-deficiency. Iron deficiency is the number one nutritional deficiency in the world and women are more likely to be deficient than men. Try to eat a balanced diet as much as you can, that’s all I got to say. Meat, beans, eggs, and dark green leafy veggies are great source of iron. For potassium, you can eat bananas, baked potatoes, and oranges. I’d advise not to take potassium supplements without consulting your doctor as a little too much can cause serious complications like heart dysrhythmias.

To answer your question about calcium supplements, I’m assuming you’re a young adult, so, I’m going to suggest drinking reduced fat/skim milk or calcium fortified orange juice rather than taking supplements. Now there is new Yoplait yoghurt with 50% daily value calcium. A recent study found that calcium supplements in older women only make a difference for the first few years of therapy.  There is too much we don’t know about supplements and they increase your risk for kidney stones.