Honestly would recommend a therapist. Brain fog isn’t always chemical or neurological decline. Cognition on a particular subject can fade for any number of reasons and most of the ways that are fixable involve learning to work with your own mind.

I lost some ability to code regularly a few years ago and found after a long while of looking that I had a dissociative disorder. Nowadays I can code better than I did before. Drugs were not the path that worked for me, but I consider them valuable for stabilization if needed so that work can be done.