What Causes Sharp Pain In Upper Rib Cage Area While Sitting Or Bending?

Hi,i am 30year old, 130lbs, not pregnant and for awhile now have experienced a weird sensation on my left upper ribcage area, just below breast. Feels like something is loose and moving. No visible lumps and cant feel anything strange. If I bend over to far while sitting or standing I get a very sharp pain and have to immediately sit up and breath in slowly. Any ideas what this could be?