I have been running for just about 5 months on trail. I have recently been getting a very sharp pain just under my right rib cage on some of my trail runs. Strangely enough the pain seems to start when I am on a more technical or rocky trail coming down hill. Its not a cramp or gas pain feeling its more of an extremely sharp pain that will stop me dead in my tracks at times. Today I tightened my abdominal muscles took my left hand a pushed against the area under the rib cage which relieved enough pain to finish my run. Its not a constant pain and I don't always experience it on runs, but it usually starts when downhill running where my body is experiencing more forceful impact. Ive never had it on street runs and I'm probably running between 25-35 miles a week which includes both trail and street. I also weight train 5 hrs per week and play football and never experienced the pain in those activities. Has anyone else experienced this? If so is there any prevention or something that I may not be doing correctly?