Awakened at night with sharp stabbing pain left upper back. what could it be?

Sharp left upper bac: Many potential causes: rule out cervical or thoracic disc herniation vs acute muscle strain of paraspinal muscles vs facet joint sprain vs referred pain from other area especially abdomen/diaphram which also refers pain into upper back. If this persist, you need an md to fully evaluate. Try rest, antiinflam meds, localized heat, massage and if not better evaluate by md and ? Mri vs injections.