Ringing of the ears(tinnitis) is often caused by a magnesium deficiency. It might also be caused by a deficiency of another mineral such as zinc, or by a vitamin B12 deficiency.Mercury may cause an overgrowth of candida, which may lead to malabsorbtion of minerals and vitamin B12 even if you are ingesting enough. You could try taking supplements of magnesium and zinc together with vitamin c, using a sublingual B12 supplement (dissolves under the tongue for better absorbtion) ,and if you are having trouble with candida, try taking steps to bring it under control.