Im Having Terrible Achy Legs. Ive Always Had Lower Backaches

Im having terrible achy legs. Ive always had lower backaches so i dont know if that is part of it. I have also gone to the ER before for crampy legs and the results were always low potassium. I have been using heat which helps a little bit i also took advil which isnt working. I just dont know why they feel so achy!