Congrats on day 5, Mat
I remember that first week well, as it wasn't too long ago. It really surprised me too: things like feeling clumsy, foggy, forgetful, tired but not sleepy, kinda disoriented (among other things). The days went by slow and the nights even slower. The next week things got better steadily, but on some days the above symptoms would return.
I read somewhere that if there is any stress at all, it makes it seem much worse. Our brain is resetting itself after being influenced by alcohol for a period of time. Hang in there and if it gets worse, see someone about it!