Suggest Treatment For Tiredness And Heart Palpitations

I am allergic to oranges, I have been since birth it puts to sleep almost immediately therefore I cannot take a multi vitamin, I also am b-12 and iron deficient and low magnesium. Am I having absorption problems and who should I take to about it. My Internist let me go with a 114 b-12 level for over a year and told me it was just depression causing my tingling, tiredness and heart palpatations.