I had Erbitux also and am in my 2nd month of recovery (from the side effects) from both the Chemo and the radiation. One of the side effects has been "Chemo Brain", a condition similar to CRS (can't remember stuff). My wife noticed my fogginess about the 3rd week of my 7 week treatments and I still have it; along with some others. My dr.'s are telling me that it may take 4-6 months to get back to where I was before. I am hopeful, but I am not completely sold that I will ever be the same as I was before; not in that time frame.