How does one get a doctor to test for B12 deficiency (MMA Test) when with all of the symptoms I am having...........they think it is mental illness? I have ask for the test from 2 doctors and they each say..........have your other doctor test for this. Symptoms are burning feet & hands, pain, numbness and tingling in arms hands legs feet, feet and hands feel like having socks on with pain numb tingling, foggy, memory loss, gait disturbance at times and more. Thank you.