I have had pains in the calf of both sides of my legs. I woke up this morning and they were so cramped I was in tears. I take potassium daily (have had a history of low potassium). I noticed I was short of breath today but it s also below 0 and windy here. I spoke to the nurse at work who told me I might also need magnesium but to see my doctor about blood tests. What could be causing this? (I m a 60 year-old female).