Hello Friend, Good that you are seeking a help here. Your brain fog is due to mental stress and bot due to your reasons you think.
Just analyze other changes happening in your life like career, job stress, relationships or family issues. Some of these could affect and cause emotional disturbance.
Don't worry. Take a counseling guidance to assess yourself first to figure out the actual reasons and suitable solutions to overcome.
Next Steps
Consult a psychologists directly or online. Feel free to reach out to me online to discuss this issue in detail. Be positive. You will be alright soon.