@blossom, big hugs back to you, I was so overwhelmed to read your message. Thank you so much from my family, for all the empathy. You wrote to us like family and brought tears to my eyes. Much love to you. All your inputs are well taken.
We followed up with the doctor yesterday and the advice was to start learning science and math subjects little by little, pacing them as much as he can tolerate just so the channels in the brain open up or get exercised in order to restart working optimally. This may lead to worsening of symptoms or let us understand where he stands now. She expects him to recover from the lingering symptoms over time as he continues to do physical therapy, take supplements, and sleeps a lot or as much as he needs to and does not push himself too hard with anything. So we are going to self-study at first to see how he does, before starting any new courses.
We so very much appreciate your suggested plan for him. Hugs! We are definitely thinking similarly. Thanks again.