I am a teacher of Ananda yoga and practice a traditional Ananda practice at home. Sometimes when in meditation in my own practice and sometimes when I am guiding a meditation in class I experience, what can best be described as, dizziness. It is not uncomfortable or unenjoyable. On the contrary, it is intoxicating. It feels as though my body is moving in a counter clockwise circle. I simply dive into the experience, breath, and offer it upwards. Why might this be happening?
The phenomenon you describe is likely a rising of kundalini energy, which does indeed tend to spiral as it moves up the spine, sometimes inclining the body to move in circles along with it. Although it’s a good thing — spontaneous rising kundalini is usually associated with spiritual growth — you are right to offer the experience upward. It’s simply happening, but it’s not something to involve yourself in, consciously, whether through bodily movement or even through paying close attention to the movement of energy. Otherwise one can all too easily get caught up in phenomena rather than true spiritual growth. Simply offer it upward as you are doing, with gratitude that good things are happening, and keep meditating.