What Could Cause A Painful, Bubble-like Air Pocket In My Groin?

I have a air pocket that I can push on and it sounds like bubbles coming out of it on the left side of my groin. It gets so painful sometimes it will double you over and last for several days.. I ve had a CAT scan with contrast they said they didn t see anything I ve been to general surgeons said that there s no problem down there it s not a hernia or lymph node I m at my Wit s end I don t know what to do or what doctor to go see after three doctors I m at a loss