There is an excellent description of the Blastocystis hominis infection on the infectious diseases section of the Mayo Clinic web site. It's not clear whether blastocystis infection is actually an infection or that it causes any abdominal signs and symptoms.
It says "If you have blastocystis hominis in your stool but no signs or symptoms, you don't need treatment. Even if you have symptoms, the blastocystis infection may clear up on its own. If you have signs and symptoms that don't improve, you can take medications that may help, but the medication isn't always effective."
How were you diagnosed? What did your doctor recommend?