Pinched Nerve in Lower Back

If this pain persists you better see a physiatrist or orthopedist that specializes in the back. Halt all compresssive exercises. See my lengthy post on training with a back injury, herniated discs to be specific. 5/3/1 & Back Injuries - #13 by BrickHead
Also see Dr. Rusin’s guide to training with back pain on his site.