Chapter 23Difficulties of the Physical Nature · Giddiness
Book 7. Part Three: Sadhana on the Physical, Subconscient · Section One: Sadhana on the Level of the Physical
For the giddiness, it may be that in concentration you go partly out of your body; then, if you get up and move before the whole consciousness has come back, there is just such a giddiness as you describe. You can observe in future and see whether it is not this that happens. One has to be careful not to move after deep concentration or trance, till there is the full consciousness in the body.