I can relate to the sympyoms you describe - I am trying to study and find it reallly hard to concentrate when I am feeling like that - well not hard, impossible! It happened recently in a session with my T. So my T asked me to concentrate on an object for 10 -20 seconds, then concentrate on my breathing fro 10 - 20 seconds, then concentrate on the object, then concentrate on my breathing - we did this for just about the whole session and it did stop the spinning and numbness in my head. It is a really horrible feeling isn't it and really annoying when oyu can't break out of it to do other things. Good luck, stick with it.