you've just had major surgery, and your body is in massive healing mode. Plus it takes some people longer to get over the anesthesia effects than others. I can't remember how long I had brain fog (it's been over eight years since my surgery), but I do know I seemed to get better and better every day. It took about two months before I felt completely back to normal (I remember wanting to take naps in the afternoon for quite awhile..), but again, you're in the worst part of it, so you won't have brain fog that whole time, fortunately. I'd give it a few more days, though....