[anonymously]

I would listen to your vet or consult an Internal Medicine Specialist. I think your money would be better spent that way rather rather than going homeopathic.

http://skeptvet.com/Blog/category/herbs-and-supplements/

http://skeptvet.com/Blog/category/homeopathy/

Prognosis
“Even with treatment, it is possible that only the cystic form of Giardia has been removed from the feces, while the infective trophozoite form in the dog’s small intestine remains. In other words, fecal tests for Giardia can be negative, but the parasites still can live inside the dog’s gastrointestinal tract, making those dogs a source of potential infection for other animals, and possibly for people. Giardia is rarely deadly in otherwise healthy dogs. Dogs infected with this parasite typically have flu-like symptoms that eventually resolve”.
Above paragraph is an excerpt from:
http://www.petwave.com/Dogs/Health/Giardia/Treatment.aspx