Dear win,
Amebiasis can cause inflammation and ulceration of the colon. The diagnosis, however, is usually not made by sigmoidoscopy but rather by the detection of the organism. Some individuals may be asymptomatic carriers of the organism.
The symptoms that you describe are not typical for amebiasis. Amebiasis presents with diarrhea and bleeding. The question to ask your doctors is whether the symptoms could be due to other conditions.
This information is presented for educational purposes only. Ask specific questions to your personal physician.