Hi.. I am an 18 year old as well and I can relate to you in that you are nervous to go to doctor. I have just recently got an MRI of my brain and i was freaking out too. I have another appointment tomorrow and im worried but try to calm down and think positive. thats what everyone says to me! you might just have a n inffection it might be something simple soo no worries feel better friend
I had my first visit to a gastroenterologist about a year ago. I was living in europe at the time so it might be different for you if you live in the U.S. or depending on how the doctor runs his/her office.
My first visit did not involve any kind of examination. Just a discussion of tests that would follow. For me this meant a colonoscopy, but this happened at a later date. I can't imagine that they would do anything invasive on the first visit as most tests require you to prepare in some way. They certainly won't do anything to you without explaining it first.
I would think the physician will examine you by listening to your abdomen with a stethoscope and possible feel around on your abdomen in several areas and yes there might be a rectal exam. More than anything the physician will want to know when this started, how long it has been going on , if anything makes the condition better or worse. What you have been eating and if you have been out of the country in the last year and what medications you are taking. good luck!