I have lower back pain when i breathe in. i went to the doc and they gave me a urine test. nothing showed up. any idea what this could be?

How long is the pain: Pain lower back on deep breathing, coughing, bearing down for stool raise concern to r/o spine/disc related problems. If you do gym work ups vigorously, faulty postures.excess wt. lifting etc can cause musculoskeletal strain /sprain which can cause similar pain. Better consult your PCP and r/o these things, also get r/o kidney stones. Kidney stonescause pain usually on one side of midline .