I'm scared...need help please?

i've been having intestinal and esophagus issues, so my pediatric gasteroenterologist is having me do some tests. she listed swallowing barium, upper gi, endoscopy, and possible colonscopy (dont know how to spell it). ive NEVER had health problems and im not even in highschool yet!! freaking out here...can anyone tell me what to expect in these tests, it'd be really appreciated