This is great! It sounds like you were really able to tune into this diaphragm, and allow old, stuck energy that was there, to move. This explains the sense of cold and numbness at first; noticing the stuck, or ‘frozen’ energy, and then the physical sensations of heat and jerkiness, which is a common experience of sympathetic nervous system (fight/flight) discharge. It’s really great you were able to stay with this, and allow the emotions to emerge! That helps flow come back into the system, and that’s what it’s all about!