After using emotional mastery 2.0 and internal alchemical crucible my body released a lot of heat. Now whenever I play any physical fields my lower back abnormally heats up and that sensation also travels to the legs. This heat arises only when listening to fields.
you used the Internal Alchemical Crucible, which is a combination of Mula bandha + Uddiyana bandha + Jalandhara bandha . These three bandhas performed simultaneously constitute the so called Maha bandha, which is a very powerful yogic technique that, among other effects, awakens kundalini, so you may have a little of that effect Congratulations.
The burning sensation in that area and radiating to legs, and even feet, are signs of the awakening of this energy. If you continue, the immense purification power of Maha bandha will purify your nadis (subtle energetic channels in the body), and make it possible that your kundalini awakens more, and starts to ascend with less blockages in its way, so safer.
Keeping the spine straight and vertical when listening to it, helps even more.
The Acu-Automaton also helps, and intercession fields
This could even trigger headaches and aches in the body. Take a break from fields for couple of days.
You can just try grounding by walking midst trees and water. For fields my suggestion is acu-automation , Devic Intercesssion and grounding.
Cold showers will help a lot. Drink lots of water.
Congratulations.