Good news! Like Victoria said, you don't want to have IBD. Although I do understand what it is like to not have answers. Sometimes you almost wish they would find something so that your horrible feelings and symptoms are vindicated. You're very lucky to have gone to the Cleveland Clinc... that and the Mayo Clinic are supposed to be a couple of the best in the country.
I have not tried any anti-depressants for my IBS. I wouldn't be opposed to it though. There is a lot of research that shows how beneficial they are for IBSers. I think many of us are natural born stressers... maybe there is a connection to IBS and tense people.