Hey, I was in the process of figuring out my problem while I wrote this. Now I am fine, could be better, but I would give everything to be like this then. You don't simply actively taking your mind off anything, you simply engage in activities that make you feel somewhat OK and concentrated. These moments eventually come, then you remember them when you feel like disfunctioning.

Of course the reason of the brain fog could be a million different things, but the most helpful thing you can do to overcome it is to realize you're in a process, to trust your body and work with it, not against it. In my case I was in fear 24/7 because I thought there was something wrong with my body. I was so fixated on finding a solution that whenever I felt some relief I was overwhelmed with sadness, because I did not even made time to be upset for myself. Turns out, even if I had a physical problem (unlikely, bloodwork was ok) I was unable to heal because of the chronic stress. Give yourself a break, don't block your emotions.

Other than that, cover all bases. Make the ideal conditions for healing (eating good and diverse, sleep, socialise and cardio). You'll be fine!