Test thru Metametrix GI Effects Stool test (panel #2105), only test worth doing. There can be many pathogens that can get into the GI tract, and it is best to correctly identify the problem and treat accordingly. Guessing can be harmful if you are bombing with pharmas, but then again you might get lucky. I prefer to know what I am dealing with then bomb.
The naturopath treatment probably is not going to do much. CS will not touch many of the parasites, might do something if bacteria is involved, maybe for lower-level protozoa (giardia) but nothing for sturdier forms of protozoa. Bitters help stimulate gallbladder/liver which can be helpful but more than likely not kill parasites directly.