I too have this pain 'like it is going in to a charley-horse'... for the last 6 weeks. It is in my left calf (behind my knee) and hurts 97% of the time. The pain stays basically the same and always in the same place. I had ultra sound of veins and arteries done today and both are good!! My family history is low in potassium, guess I will have that checked next. My main concern was to eliminate DVT and PAD. Anyone else have any new feedback? Thanks