Has anyone experienced IM methylcobalamine NOT working?? I switched from cyanocobalamine about a month and a half ago and many of my PA symptoms have returned: headaches, heart palpitations, and my blood work now shows low level of red blood cells and large red blood cells again. The blood work looks like it did before I started cyanocobalamine injections for my PA!!!! My serum B12 levels are high tho, 2000. I switched to methyl because it's the active form of B12, has no cyanide, is supposedly absorbed better and crosses the blood brain barrier. Could it not be working for me though?