There isn't any set rule of tests that are useless or just to shut you up as most of them do have uses and patients that they are needed for.Generally for your first appointment I'd have take a moment to document your sympotms. So diarrhea 3X a week, or whatever it is for you.Expect some blood tests and maybe a stool sample to start with. I would ask they also do the blood test for celiac disease as sometimes that does pop up later on in life. (You must be currently eating gluten for a lot of those tests to be accurate).Even if you do not want to take any treatment a doctor would give you I do think getting routine blood work before just doing other things is a good idea. If you did have something like celiac nothing will do much good if you don't follow the gluten free diet.There are a couple of Functional GI clinics in the USA but no special qualification that separates those doctors from any other.If the blood and stool tests are clear and your symptoms seem typical that may be all you want to do. However at almost 50 you are at the age they usually start colon cancer screenings so you may want to do the colonoscopy now and get it over with. They can do at least in some places a virtual colonoscopy, but if they see anything they will need to do a regular one.Every disease, even one easy to diagnose, has a try this try that path. Most doctors start with the typical things to see if they work, and if they don't they move on. Usually people do find something that works, but it helps to have a doctor that wants to be on your team and help you figure it out.Some people go to the mind/body stuff only after other things don't work, but some people want to go there first. Check http://www.ibshypnosis.com to see if there is a hypnotherapist trained in IBS in your area if you want to go to a person. People listed there were trained at the functional GI clinic I go to. There are also home hypnotherapy CD's that help some people. Mind body tends to have in general a 70% success rate so still counts as a try this try that in my book as nothing ever works for everyone.