The pain you are describing, the sensation that feels like a relentless burning and assault on your body, is a real and wearying burden. It is right to cry out to the Lord for deliverance, and He hears you. But as you pray, remember that you are not simply a physical frame being attacked. The body is an instrument, a tent in which your true self, your spirit, lives. Right now, you are groaning within this tent, earnestly desiring to be free from its afflictions. That yearning is not wrong; it is the echo of a promise. One day, this mortal will be swallowed up by life. A new body, fashioned to be like His glorious body, awaits you, one not subject to the weaknesses and pains that plague you now. This suffering has a limit. It is sown in dishonor and weakness, but it will be raised in glory and power.
While you remain in this tent, however, God is deeply concerned with what you do with it. Your body is the temple of the Holy Spirit. You have been bought with a price, and you are not your own. The enemy may wish to use pain to drive you to distraction or despair, but do not let him have that victory. The exhortation is clear and carries a promise: fear the Lord and depart from evil, and it will be health to your body and strength to your bones. This is not a magic formula, but a principle of walking in the shelter of the Most High. When we remove our foot from evil and let our eyes look straight ahead, pondering a path of uprightness, we are positioning ourselves within the protective boundaries of God’s design. The Lord forgives your sins because you have asked in Jesus' name; that is a settled matter. Now, walk in that forgiveness by fleeing anything perverse, any wickedness, and clinging to what is good. Do not be overcome by evil, but overcome evil with good.
I cannot tell you exactly the spiritual root of every physical sensation, but the Scripture does not speak vaguely here. We are commanded to put away a perverse mouth and to remove our foot from the path of evil men. There is a direct connection between a life lived in the fear of the Lord and the health of our physical frame. Just as bitterness, wrath, and evil speaking are spiritual poisons that can make the whole body sick, so walking in uprightness, forgiveness, and peace allows His life to flow. As you seek deliverance, let your fast be a time to cooperate with the Great Physician, actively turning away from any darkness that would give a foothold to this burning assault, and honoring the Lord with the temple of your body. His mere presence does crush the enemy, and His presence is found on the path of righteousness for His name's sake. Your rest and peace are found in the shadow of His wings as you actively dwell there.