Hi, on November my b12 was 105 and the doc put me on the cyanocobalamin tablets, by January b12 was down to 101 so now he says I should have been put on the injections which due to nurse availability at the surgery I just started this week, Mon weds and today. After first injection I felt awful, went home crying and slept for 2 hours. 2nd one wasnt too bad but I have had a headache since Monday, really bad around my left eye, up and over my head and in my neck. I'm a bit concerned now as b12 is so low and was making me feel terrible now what is supposed to be helping is possibly what is making me feel worse! Has anyone else here had this or know what I can do to help it?