Hi, I suddenly began having random, but very localized stabbing sensations in my mid back, left side, near my rib cage this morning. No other symptoms. But when it stabs is makes me slightly jump and groan. I can place exactly where it is. And I may go a few hours without feeling it, then I may feel it just once or multiple stabs in sequence, 10 or so seconds apart. I am 36, relatively healthy, 5 4 , 148 lbs, but do take blood pressure for inherited HBP. Walk 3-6k steps a day on non-gym days. Just recently started a workout regimen at the gym of elliptical and leg exercises, but have had nearly no soreness on the muscles I m working. Never had a kidney stone, but could this be that? Pulled muscle from Monday nights work out? Many thanks.