There's nothing fun about dealing with gastrointestinal-related illnesses. It's painful, uncomfortable, infringes on your everyday life, and can be quite embarrassing, even though it shouldn't be. If you feel like something is wrong with your stomach or your intestines or anything like that, the obvious thing to do is immediately head to a gastroenterologist. These specialists can diagnose what's wrong with you, give you medication to help make you feel better, and soothe your worries. First, though, they have to run a battery of tests on you, including a stool sample: as gross as it might sound, there are a bunch of health issues that can be detected from your poop.
Collecting a stool sample is not fun or easy, and it's probably something you'd like to avoid! Unfortunately, if your doctor recommends one, you should listen to your doctor's advice and just get it over with it — it can help detect some serious issues that need to be dealt with immediately.
Of course, a stool sample isn't the only way you'll be able to tell that something is up with your body. You can probably tell on your own, whether you're monitoring your feces or realizing that, uh, things don't seem quite right. Maybe you're pooping way more than usual, maybe you can barely poop at all. Whatever the specifics, you'll know if something is up. Below are a few of the illnesses that could be detected by paying attention to your poop: