Vytorin and intestinal absorption.........

I have taken Vytorin for the last three or four years. Just over a year ago, I started having all kinds of issues ranging from headaches and nervous twitches to complete blank spots in memory. After a LOT of tests, such as MRI's and MRA's, a blook test finally showed that by B12 level at below 100 micrograms. Taking the B12 pills did not help. So now I take a 2000 micrograms self injection once per week to maintain a healthy level of B12. I read that Vytorin is known to cause problems with intestinal absorption and I wonder if that is what caused my body to completely quit absorbing and using the B12 found in the normal foods I eat?