Sudden severe pain in the lower right side of the back male 45 and feeling of need of defecation even after large bowel movement?

May need the ER: Sudden severe pain means a trip to the ER for most people. The more common causes of lower back pain include: back muscle strain, back ligament sprain, fractured vertebra, slipped vertebra, herniated disc, spinal stenosis, spinal arthritis, urine infection, kidney infection or stone; tumor in the spine, kidney, or elsewhere; fibromyalgia, etc... It's such a long list of possibilities.