When you consult a doctor, the following steps will be followed for diagnosis:
Medical History: Your doctor will note down the history of your health problems, medications you take, diet recall and environmental factors that might have contributed to this infection.
Blood Test: Depending on the basic details, your doctor will suggest some blood tests. A complete blood count test is suggested in case of diarrhea.
Stool Test: In case your doctor suspects that a bacterial or parasitic infection is the cause, they might suggest a stool test to confirm the same.
Flexible sigmoidoscopy or colonoscopy: This test is performed with a device that is inserted into the rectum that allows the doctor to see inside your colon. It is also equipped with a tool that allows your doctor to take a small sample of your colon for further tests.