Hi Dr. Matthew, I Have Had These Symptoms For Many

Hi Dr. Matthew, I have had these symptoms for many years - lethargy, cramps, restless legs, tiredness, headaches and pain in back (recently). Ever since I started Magnesium supplements, the pain is very controlled and limited. But since Mg oxide absorption is poor I suddenly get back symptoms all over. Question is : How long should one take Mag supplements before Mg deficiency can cured ? Do I have to take it life long or would some blocked channels of absorption open up due to strong intake ?