It's one of the symptoms that are triggered by acute Nathan withdrawal, later on you will get anal nausea, loose bladder control and start thinking your a Swedish butterfly. All of us are going through the symptoms in one way or another, hang in there and just try and cope the best you can.
If the hallucinations are getting too strong for you to hande than it may seriously be time to consider some alternative treatment options. I am saying this in your best interest here, there are a couple Nathan withdrawal centers around if you look for them and I believe George is setting up a psychiatric self-help guide as we speak. It will be hard at first, but you just have to realize that he is gone and there is nothing you can do about it.