I pinched a nerve in my back when I slipped in poor posture during squats while I was working out once and I had a similar sharp pain near my groin as well. The location of the pain itself varied; at times it felt like it a nut, other times it was just the back, and other times it ran along my lower abdominal on one side near my kidney, and sometimes it shots all the way across. The entire thing lasted about a month, although part of that was attributed to my impatience two weeks in and deciding I was going to work out, pain be damned.
I'd give it a rest as much as possible by limiting what motions invokes the pain and giving it a few weeks. It should pass after that; stretching in my experience only alleviated the pain briefly.