I think I meditated some wrong way in a long meditation on Mahashivratri. When I woke up the next day the left side of my upper back- heart chakra onwards- was soar till the point on the neck adjacent on the left side to the medulla. A day later, the back is better after energization, but the "epicentres" of the pain are points on the left side next to the heart, throat and medulla chakras and some discomfort in the left eye. What is this? How do I heal this spiritually? I am a Kriyaban.
If you are feeling physical discomfort, I think it’s safer to assume the cause is also physical: meaning that during a longer meditation period your posture and head position must have been off slightly with perhaps some underlying tension. After holding tension for a long but unnoticed period, the muscles in those areas are sore. Careful practice of the Energization Exercises should indeed be helpful, but it will probably take a few days or a week more for the soreness to dissipate. I’m not a healthcare person, a massage therapist, etc., but it might be good to consult with someone and see if some actual massage or manipulation will bring relief.
From your report, it doesn’t seem like it would have a metaphysical source, nor be related to Shivaratri. “Anything’s possible,” of course, but your description sounds more physical than metaphysical.
In longer meditations over the years I, and many others, too, have had some back soreness, and neck or other forms of tightness from sitting with focused concentration for long hours, ignoring the body, and remaining inwardly in devotion and prayer. Sitting completely still for long periods is a strain on the body, muscles, and tissues when they are unaccustomed.