I personally think that since you are having altered bowel movements ever since you had your hysterectomy done, you could be having infection with an organism called C. difficile.
This bug can cause diarrhea and happens particularly after a surgery or a procedure during which antibiotics are routinely given to the patients.
Antibiotics used during surgery can alter the normal, helpful bugs, in the intestine which causes overgrowth of C. difficile causing diarrhea like what you are having.
There is no harm in giving a seven day course of flagyl (metronidazole), which is the treatment for C. difficile, for your diarrhea to see if it helps you with your diarrhea.
Testing for C. difficile toxins in the stool is also recommended, so if you have not had that test done I would recommend that you should have that done.
If your symptoms do not respond after a course of flagyl I would recommend that you should have a colonoscopy done to have a look inside your colon.
I would also work up you for celiac disease which can cause diarrhea for a prolonged duration.
You should ideally be referred to a gastroenterologist for this.
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