My lower back started to hurt really bad & sharply as if a nurve was stuck & it projects to the left lag. how can i ease the pain quickly?

Radicullopathy : Pinched nerve or "sciatica", most commonly due to a slipped disc. Short period of rest, application of ice to the back & nsaids (e.g. Ibuprofen) if no contraindication may provide some relief. Acute presentation of severe pain is a good reason to go to the er or urgent care, specially during after hours. Injection of ketorolac can help. Usually needs more evaluation & therapy thereafter.