Hi Lawgirl, I had a colonoscopy, barium series, and blood tests prior to being diagnosed. I was having other problems, too, including joint pain and a mild concussion resulting from a fainting spell, so a rheumatologist and a neurologist were also involved at the time, making everything that much more confusing... but in the end, my GI doc diagnosed mild Crohn's colitis and that was it.
I agree with Eva that the hardest part of the colonoscopy is the prep... for a couple of days before the exam, my doc's instructions advise to eat bland, low-residue foods (basically stuff that's easy to pass and not irritating). Then, the day before the exam, you do not eat anything at all; your doc will provide you w/instructions about what you'll need to take that day to clean out the digestive tract, and you'll only have liquids. Some doctors' instructions vary a little from others, so you'll want to follow the plan that your doc recommends.
I have never had trouble with a colonoscopy, but I know that some people have... I think it depends a lot on how extensive the disease is and how well you respond to anesthesia or sedatives, depending on what your doc uses. The facility where I have my procedures uses a type of anesthesia that puts the patient "under" very quickly and also causes you to wake up quickly afterward, but I'm completely asleep during the test.
Hope this helps... do contact your sister and aunt if you can and let them tell you more. It will do you good to be in contact with family members who have been through this. I have an aunt who has Crohn's as well. Best of luck to you and do ask more questions here if you want.