Lower right abdominal pain - 6 months

Hi
my sister has had a constant pain in the side of her abdomen for over 6 months now. Her gynacoleagist ruled out anythign to do with the reproductive system. She has just undergone a colonoscopy which came back clear but the pain became worse when on the laxative medicine for the colonoscopy. The doctor suggested irritable bowel - but as it is a constant pain i think this is a cop-out.
She has been tested for chrons? and was all clear.

Any thoughts

[Gina04]

Has she had her kidneys checked out at all?