The colonoscopy might show something, but it probably won't. However a colonoscopy is a good idea to make sure nothing more serious is going on. Have you tried making dietary and lifestyle changes?
Get a blood test! And maybe go to a naturopath, they're more helpful then doctors when doctors can't give you any answers. My naturopath said I probably have a food sensitivity so I took a blood test and found out I was allergic dairy! I cut dairy out of my diet and I now feel absolutely fine!! I thought it was maybe meat or wheat, i never even thought about dairy! I would recomend getting a blood test to anyone who has IBS :) For more information: http://www.rmalab.com/index.php?id=2
Did your regular doctor ever give you a RAST blood test?
Yes I've made dietary changes. I eat much healthier. I'm also doing fiber supplements and such as needed. I don't touch anti diarrheals bc ill never be normal again. I'm not sure about a RAST or what that is. They checked my organ enzymes and everything was normal. I always just thought I was healthy and sane until recently lol. I'm 24 not terribly over weight 135 lbs or so and I quit smoking this past spring. So I'm baffled.
Have you tried eliminating 100% of all lactose from your diet for 2 weeks? Have you tried eliminating 100% of all gluten from your diet for 2 months? Have you tried increasing your water intake? Have you tried increasing the amount of exercise you get? A RAST blood test is a blood test that tests for many allergies.
I did have the colonoscopy and it is horrible making my immune system haywire. According to the result i have they said nothing wrong my my intestines are real sensitive.