Adante: I was hoping you were going to say, "At 5 months things are great!". :- (
Sorry not to be more of an inspiration -- I was speaking only of my personal experience. It seems like most others here have no problems with motivation or ambition, which should be encouraging for both of us.
For me, the "brain fog" is in part a general inability to think straight, but specifically I have trouble making connections or sequencing thoughts properly. For instance, planning and executing complex projects (like a home improvement or a complicated car repair), used to be easy and enjoyable for me, but is now impossible.
Other than doing what you can do to promote healing and recovery (which it sounds like you're already doing), the key word is PATIENCE. As the saying goes, "Time Takes Time." 7 weeks is still pretty early. Hang in there!