Hi
Welcome to the MedHelp forum!
From you symptoms alone it sounds partially like chronic fatigue syndrome. This usually presents with widespread myalgia and arthralgia, headaches, chronic mental and physical exhaustion, cognitive difficulties, concentration difficulty and memory problems.
Then you also need to investigate other causes of brain fog like liver dysfunction (get liver enzymes done—liver function test), kidney dysfunction (get kidney function test done), and anemia. Poor sleep pattern and sleep problems like sleep apnea too can cause brain fog. Sleep studies by sleep specialists can help diagnose this.
I think you should discuss these possibilities with your doctor. It is difficult to comment beyond this without examining. A comprehensive investigation is required keeping all the points in mind.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Sounds like Accutane clouded brain.
I would definitely have your thyroid blood levels checked. This is one of the symptoms of low thyroid.