My tongue is sometimes swollen. It has cracks down the middle and is sore most of the time and burns sometimes. I am healing from gastritis. Does anyone else have this tongue problem? I am 55 years old and would also like to know how long I can expect to see the positive effects from taking a b12 oral supplement. I am exhausted all of the time and by the end of the work day I struggle to stay awake. How much daily b12 do you recommend?