I was diagnosed with b12 deficiency 6 weeks back. My B12 was 144 Pg/ml. Doctor gave 1500mcg sublinguals and 5 injections every 5 days of 500 mcg. I went to doctor and he told me to do test again. This time it was 1767 Pg/ml. He is not sure why my brain fog is not going. He told me stop supplements for 2 weeks and start again and gave me Xanax for relief. What shud I do?