You may want to check out adrenal fatigue or defficiency. That was my problem. Low sodium made my potassium too high. Adding 1/4 - 1/2 tsp. Celtic Sea Salt to several glasses of water a day has solved the problem (along with supplements from Dr. James Wilson, author of Adrenal Fatigue).
Corticosteroid deficiency can lead to many problems. For example, when corticosteroids are lacking, the body excretes large amounts of sodium and retains potassium, leading to low levels of sodium and high levels of potassium in the blood. The kidneys aren't able to concentrate urine, so when a person with a corticosteroid deficiency drinks too much water or loses too much sodium, the blood level of sodium falls. Inability to concentrate urine ultimately causes the person to urinate excessively and become dehydrated. Severe dehydration and a low sodium level reduce blood volume and can culminate in shock. (http://www.cushings-help.com/adrenal_glands.htm)