I've had on and off lower abdominal pain, slightly to the right, in the hollow of my pelvis iyswim. It kind of feels like trapped wind, but I know it isn't, I've had trapped wind and it stays there for a few days at a time and doesn't move (which whenever I've had trapped wind I know it does eventually come out :o)
My mum says it might be a grumbling appendix. She had it for years before eventually getting full blown appendicitis. Quite a few members of my family have had appendicitis (not sure this is relevant though)