I agree with nickie. I had those symptoms in my first trimester. I thought it was lack of electrolytes and started drinking Gatorade. Came to find out I was pregnant instead :0)
I definitely have those symptoms and have had them every single time I have been pregnant. I tend to get sore thighs (upper and lower calf) and cramps in my lower legs and toes =) Usually it is caused by a deficiency is a vitamin that you need-- try eating some bananas or drinking more OJ and that could definitely help you out. If you aren't taking prenantal vitamins yet then you might want to (even if you find that you aren't pregnant) it could definitely give you a boost in your vitamins =)