Anxiety Support Group
Anxiety is a physical condition marked by intense and persistent feelings of distress, fear, angst or dread. General anxiety caused by routine day-to-day stresses usually passes quickly and is experienced by almost everyone at one time or another. However, such feelings that linger over time and are very difficult to cope with, and which lack a clear cause, may indicate...

"Brain Fog"... Is very symptomatic of anxiety. There is a reason for it. This is a reaction to the body being in ha high state of stress and anxiety. As you can imagine with the high amounts of adrenaline and cortisol running through your system...something's gotta slow you down eventually....brain fog seems to serve this purpose. Some people describe it as an "unreality" or "out of body" or "spacey" experience.
Try getting into an exercise routine which will both increases you endorphins and also helps to lift depression. Nothing gets rid of brain fog faster then exercise.
I haven't found any way to get rid of it...I wish I could help you. If I am at home and having brain fog, doing some light stretching/yoga seems to bring me down to reality. Also, talking to someone close to me (like my mother) or listening to music also helps. Unfortunately, I can't really do any of those things while I am in class, so I haven't found a solution. I hope you find something that works for you...I know how miserable and frustrating this is.