Lower left side of my back, feels about the side of a palm when pain occurs. usually when leaning off to the side ( propped up on my elbow) pain feels like a burning or a bad pulling. only left side.

See a doctor: The pain sounds neurologic in description. It could be a pinched nerve in the back. Start with a doctor visit for an exam. Can use pharmacy meds like Tylenol or ibuprofen as labelled on the bottle. Avoid the position of pain.

Muscle strain: Sounds like you have a muscle strain in the lower back. Exacerbated by the malalignment of the spine when propped up on your elbow, causing a stretching of the lower back muscles.