I notice you are 51.
IBS can not be diagnosed without ruling out everything else.
From the past, IBS was alwayss a "diagnosis of exclusion." Excluding everything else. While the view on this has changed, and the diagnosis does not need testing in younger individuals, at age 50 you cross lines with the recommendations for colonoscopy, or flex sig, or anual stool testing for blood. In the case of a change of bowel habits, at age 50, a colonoscopy is recommended.
New diarrhea, without a found cause, indicates that you should have a colonoscopy
This should have been done at age 50 typically.
It needs to be done if it has not, as IBS can not be diagnosed properly without it at this point.
IN addition, you might well have IBS [it would be a rather late age onset] and have a colon problem which does not get diagnosed without a scope.
Also, if they only tested for parasites in the stool, I suggest you make them get comprehensive stool cultures for bacteria and fungus.
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