I know that voice all too well. As artsoul says, that's your brain having a royal ****-fit over the fact that you're no longer supplying booze. For the time being, it's being brutal and just screaming in your face. After that, it'll get more subtle, telling you that you're cured now, so treat yourself to a drink. I'm personally getting used to the idea that that voice just might be around for a long time, and my job is to recognize it for what it is when I hear it.