You can get a fecal test done at the doctor to test for parasites. They look at the stool (poo) sample under a microscope to check for parasites and their eggs. If the result is positive, s/he will prescribe medication.
"My mission in life is not merely to survive, but to thrive; and to do so with some passion, some compassion, some humor, and some style." -- Maya Angelou (1928-2014)